The United States appealed as excessive the downward departure granted by the district court for Burns’s substantial assistance. Burns cross-appealed, arguing that the district court erred by selecting an incorrect guidelines range as a departure starting point. After a divided panel of this court affirmed, United States v. Burns, 438 F.3d 826 (8th Cir.2006), we granted the government’s petition for a rehearing en banc and vacated the panel opinion. We now reverse the district court’s departure and affirm its starting point.
I.
Burns was indicted on one count of conspiracy to manufacture and distribute fifty grams or more of methamphetamine in violation of 21 U.S.C. §§ 841(a)(1), 841(b)(1)(A), and 846. The government notified Burns of its intention to seek enhanced penalties under 21 U.S.C. § 851 that would subject him to a mandatory life sentence. In the absence of the § 851 enhancement, Burns faced a sentencing range of 188 to 235 months. Burns cooperated with the government and the government, in return, moved for a downward departure under United States Sentencing Guidelines Manual (U.S.S.G.) § 5K1.1 and 18 U.S.C. § 3553(e).
At sentencing, the government told the court that Burns had immediately admitted his involvement and had been debriefed on two separate occasions, providing detailed information on several groups involved in manufacturing methamphetamine. The court was also made aware *759that Burns had testified on two occasions before the grand jury and had provided information pertaining to several ongoing investigations. His cooperation assisted the government in establishing drug-quantity evidence against one defendant, Brad Messerly. In addition, Burns served as a key witness against a second defendant, Victor DeFoe, thereby enabling the government to obtain an indictment which led to a guilty plea. The government characterized Burns’s cooperation as timely, truthful, and complete and recommended a 15 percent departure from a 360-month sentence.
The district court rejected the government’s recommendation and departed 60 percent to 144 months: The court summarized its consideration of the § 5K1.1 factors as follows:
I’m going to use 360 months as a starting point. In this case I specifically find under the 5K1.1 factors, factor number 5, the timeliness of the defendant’s assistance, the defendant was exceptionally timely in this case. My understanding is he started cooperating as soon as he was arrested. To me that’s exceptional timeliness. While some defendants start that early, virtually no defendants start earlier than that....
So I find that his timeliness was exceptional and apparently started cooperating before he was advised of the impact of the United States Sentencing Guidelines, before he knew anything about how the guidelines might affect his sentence, before he exercised his Sixth Amendment right to have counsel present. So I think in this case the fifth factor weighs very heavily in favor of the defendant....
Number 4 does not apply, any injury suffered or danger of risk because I haven’t heard anything about that. Number 3, the nature and extent of the defendant’s assistance, in this case based on the representations of the assistant U.S. attorney, I find that the defendant provided every single bit of information he knew, so you couldn’t — the extent of the defendant’s assistance could not be greater in the sense that he provided all of the information he knew.
Now, it’s true that some defendants have greater information which leads to indictments of more people. But I don’t think that’s necessarily the test. I think the test is did the defendant provide substantial assistance on everything he knew, and in this case he did. So the defendant scores very highly on the third prong.
Defendant scores very highly on the second prong, truthfulness, completeness, and reliability of the information. There’s no information that the defendant’s substantial assistance was anything but a hundred percent complete, a hundred percent truthful, and a hundred percent reliable. So Mr. Burns scores very highly on the second prong.
[T]he first prong is the Court’s evaluation of significance and usefulness of the defendant’s usefulness taking into consideration the government’s evaluation of the assistance rendered. Here the government has indicated that the defendant testified twice in front of the grand jury, that he established the drug quantity on one defendant and led to the indictment and guilty plea of another defendant. I find that that was both very significant and very useful.
Now for some reason which the government refuses to disclose, they only recommend 15 percent, but they won’t tell me why they only recommend 15 percent. And the government refuses to indicate how any one of the five 5K1.1 factors affect the 15 percent recommendation.
So while I do take into consideration the government’s evaluation of the signifi-*760canee and usefulness, it’s hard to put any weight on the 15 percent recommendation because the government refuses to disclose how they arrive at that recommendation.
And looking back on the other sentenc-ings that I’ve had, that recommendation - is in my view substantially lower than other recommendations the government has made for similarly situated defendants.
Having said all that, I have the independent right under 5K1.1 to evaluate the substantial assistance based on the 5K1 factors as I see it.
Having taken into consideration the fact that the defendant scores very, very highly on the second factor, the third factor, and the fifth factor, I’m going to reduce the defendant’s sentence substantially beyond what the government recommends in this case. That ought to come as no surprise to the government because I have a ten-year history of doing that because I just evaluate the five factors differently than—than how the government does, and the government refuses to disclose how they do it to me.
Sent. Tr. at 12-15.
On appeal, the government argues that the district court ignored its recommendation for a 15 percent departure and that the court’s 60 percent (ten offense level) departure was excessive in light of Burns’s assistance. Burns cross-appeals, arguing that the district court should have departed from the 188 to 235 month guidelines range instead of from the 360-month presumptive life sentence.
II.
When determining a sentence, the district court must first ascertain the governing guidelines range, then consider any permissible departures within the guidelines’s structure, and finally, post-Booker, decide whether a non-guidelines sentence is more appropriate under the circumstances. See United States v. Haack, 403 F.3d 997, 1002-03 (8th Cir.), cert. denied, 546 U.S. 913, 126 S.Ct. 276, 163 L.Ed.2d 246 (2005). This case comes before us on appeal of the district court’s guidelines departure and not from a post-Booker variance. We apply an abuse of discretion standard when we review for reasonableness the extent of a district court’s sentence reduction below the sentencing guidelines or beneath the mandatory minimum sentence. See, e.g., United States v. Dalton, 404 F.3d 1029, 1032 (8th Cir.2005); United States v. Saenz, 428 F.3d 1159, 1161-62 (8th Cir.2005); United States v. Mashek, 406 F.3d 1012, 1017 (8th Cir.2005).
A § 3553(e) motion permits the court to sentence below a statutory minimum and a motion under § 5K1.1 authorizes the sentencing court to depart below the applicable advisory guideline range in determining the advisory guideline sentence. See United States v. Williams, 474 F.3d 1130, 1131 (8th Cir.2007) (citing Melendez v. United States, 518 U.S. 120, 128-29, 116 S.Ct. 2057, 135 L.Ed.2d 427 (1996)). Where, as here, a district court imposes a sentence below the statutory minimum in response to a § 3553(e) motion, the departure must be based “exclusively on assistance-related considerations.” Id. at 1130-31. Although § 5K1.1 provides assistance-related factors that a district court may consider, it is not an exhaustive list. Dalton, 404 F.3d at 1033. The § 5Kl.l(a) factors include:
(1) the court’s evaluation of the significance and usefulness of the defendant’s assistance, taking into consideration the government’s evaluation of the assistance rendered;
(2) the truthfulness, completeness, and reliability of any information or testimony provided by the defendant;
*761(3) the nature and extent of the defendant’s assistance;
(4) any injury suffered, or any danger or risk of injury to the defendant or his family resulting from his assistance;
(5) the timeliness of the defendant’s assistance.
U.S.S.G. § 5Kl.l(a).
A district court abuses its discretion by issuing a ruling that fails to consider a relevant factor that should have received significant weight, gives significant weight to an improper or irrelevant factor, or considers only appropriate factors but nevertheless commits a clear error of judgment by arriving at a sentence that lies outside the limited range of choice dictated by the facts of the case. Haack, 403 F.3d at 1004.
We noted in Saenz that “[departures under § 5K1.1 and reductions under § 3553(e) should not be untethered from the structure of the advisory guidelines.” Saenz, 428 F.3d at 1162; see also United States v. Cammisano, 917 F.2d 1057, 1064 n. 5 (8th Cir.1990) (stating that to the extent possible, the extent of departure should be linked to the structure of the guidelines). Because departures and reductions based on § 5K1.1 and § 3553(e) appear contextually within a scheme designed “to reduce unwarranted sentence disparities among similar defendants,” Saenz, 428 F.3d at 1162, and because the Sentencing Commission’s sentence adjustments for mitigating or aggravating factors fall close to the recommended guidelines, “[a]n extraordinary reduction must be supported by extraordinary circumstances.” See id. (alteration in original) (quoting Dalton, 404 F.3d at 1032); see also United States v. Maloney, 466 F.3d 663, 668 (8th Cir.2006) (“ ‘[AJbsent exceptional facts,’ imposition of a sentence that is ‘dramatically lower than that recommended by the guidelines is an abuse of the district court’s discretion.’ ” (alteration in original) (quoting United States v. Goody, 442 F.3d 1132, 1134 (8th Cir.2006), petition for cert. filed (U.S. Aug. 14, 2006) (No. 06-6079))). We note that under the Seventh Circuit’s measure of reasonableness, “the standard is whether the district court’s explanation is sufficiently proportional to the extent of the variance from the guidelines range; in other words, ‘the greater the deviation, the more compelling the district court’s explanation must be.’ ” United States v. Repking, 467 F.3d 1091, 1095 (7th Cir.2006) (per curiam) (quoting United States v. Wallace, 458 F.3d 606, 613 (7th Cir.2006), petition for cert. filed (U.S. Nov. 13, 2006) (No. 06-7779)). Likewise, we have observed while evaluating the departure from a presumptively reasonable guidelines range that “the farther the district court varies from the presumptively reasonable guidelines range, the more compelling the justification ... must be.”1 United States v. McMannus, 436 F.3d 871, 874 (8th Cir.2006); see also Maloney, 466 F.3d at 668; United States v. Bryant, 446 F.3d 1317, 1319 (8th Cir.2006); United States v. Gonzalez-Alvarado, 477 F.3d 648, 650 (8th Cir.2007).2 In sum, our *762extraordinary reduction/extraordinary circumstances formulation requires circumstances of a strength proportional to the extent of the deviation from reductions envisioned by the guidelines’s structure. As discussed below, under this proportionality standard, Burns’s ten-level and 60 percent reduction exceeds the bounds of reasonableness.
We are mindful that the appropriate degree of sentencing reduction cannot be calculated with mathematical precision and that there is a range of reasonableness available to the district court in any given case. Saenz, 428 F.3d at 1164-65. It may be that we have placed too great an emphasis on numerical or percentage lines in conducting the reasonableness inquiry with respect to sentencing reductions. Cf. United States v. Jensen, 493 F.3d 997, 1000-01 (8th Cir.2007) (explaining why guidelines range levels may be a metric superior to percentages when establishing a life sentence departure point); Wallace, 458 F.3d at 613 (explaining the Seventh Circuit’s reluctance to “distill the reasonableness inquiry into a numbers game”); Maloney, 466 F.3d at 668 (same). It may also be that the use of the term “extraordinary” suggests a false dichotomy. The term as applied to reductions should not be read to suggest a true dichotomy in which the location of an imaginary line demarcating “ordinary” from “extraordinary” may be divined by a statistical inquiry.3 Rather than representing a term of art with unique legal significance, the “extraordinary” label more accurately serves as a convenient characterization of departures that we have considered particularly large relative to the two to four offense level adjustments generally envisioned by the structure of the sentencing guidelines for mitigating or aggravating circumstances.4 Saenz, 428 F.3d at 1162 (“[T]he Sentencing Commission has concluded that most adjustments for aggravating or mitigating circumstances should be in the amount of two, three, or four offense levels.”).
In conducting the proportionality analysis, consideration of the offense levels traversed by the departure may be the method most “in keeping with our assigned role to further the objectives of the Sentencing Reform Act, because the guideline system established by the Act was designed to adjust sentences incrementally by offense level, rather than by percentages.” Maloney, 466 F.3d at 668 (finding unreasonable a variance amounting to a seven-offense-level reduction from a life sentence); see also Wallace, 458 F.3d at 613 (“The percentage reduction will always seem larger if the overall number is a small one: 24 months less than a possible sentence of 25 months would be a 96% reduction; 24 months less than a possible sentence of 240 months would be a 10% reduction.”). Nevertheless, evaluation by percentage may still be useful at times. Maloney, 466 F.3d at 668. Regardless of the method used, because Burns is a criminal history *763category IV offender, the departure from 360 to 144 months effectively constitutes a ten-level and 60 percent reduction that must be considered a substantial deviation. See, e.g., Jensen, 493 F.3d at 1001-02 (citing recent cases and their associated extraordinary reductions in terms of guideline levels); United, States v. Meyer, 452 F.3d 998, 1001 (8th Cir.2006) (citing numerous recent Eighth Circuit decisions in which departures or variances above 50 percent were considered extraordinary), petition for cert, filed (U.S. Nov. 27, 2006) (No. 06-8085); Dalton, 404 F.3d at 1033 (finding a 75 percent (or twelve level) departure extraordinary); see also Saenz, 428 F.3d at 1162 (holding that a 68 percent (or eleven level) departure was unreasonable and noting that a 50 percent (or eight level) departure would be extraordinary); cf. United States v. Nelson, 491 F.3d 344, 347 (7th Cir.2007) (endorsing district judge’s comment that a 40% reduction for substantial assistance was “extremely generous” and a “rare beast,” as a 20% reduction was “more common based on sentences that he and other judges have imposed.”).
Extraordinary circumstances are infrequently found and involve assistance going well beyond that provided by other defendants. When we have found the presence of circumstances with a strength proportional to a departure of the magnitude granted here, the assistance was of a quality that could not reasonably be characterized as anything but extraordinary. Cf. United States v. Pizano, 403 F.3d 991, 995-96 (8th Cir.2005) (providing timely and truthful cooperation, serving as a “key witness” against two co-conspirators, giving testimony that could be instrumental in seizing assets from a money laundering scheme, submitting himself to debriefings and providing grand jury testimony regarding both a close family member and a “major figure” in the conspiracy, and putting himself and his family at risk of harm from “dangerous people” by testifying). Determinations of the value of the assistance for any given circumstance must be viewed in light of the entire continuum of defendant behavior associated with that circumstance. See United States v. Coyle, 429 F.3d 1192, 1193 (8th Cir.2005). Requiring more qualitatively impressive substantial assistance to justify progressively larger departures furthers the goal of reducing unjustified sentencing disparities and yet recognizes that situations exist at the tapering edge of the assistance bell-curve that justify departures that substantially exceed the Sentencing Guidelines’s range.
III.
The district court informed its departure by considering only the § 5Kl.l(a) factors. We look, then, first at whether the court abuséd its discretion as it considered and weighed the circumstances of Burns’s assistance and whether the district court’s 60 percent (ten level) departure was reasonable given the circumstances present. We then address Burns’s contention that the district court departed from the incorrect guidelines range.
A.
The district court cites Burns’s immediate and unceasing cooperation from the moment of his arrest, the truthfulness and completeness of the information he shared, and his testifying twice before a grand jury as constituting “very, very” strong showings on three of the five § 5Kl.l(a) factors and as warranting an extraordinary 60 percent departure. With all due respect to the court’s reasoning, we conclude that the court applied improper tests to determine the weight of the circumstances for each of the three factors relied upon.
*764First, the district court improperly analyzed the timeliness of Burns’s assistance under the fifth § 5Kl.l(a) factor. The court found the timeliness and completeness of Burns’s cooperation exceptional because few defendants cooperated fully in a more timely fashion than did Burns. Although few defendants may participate earlier than did Burns, if a sufficient number participate in a similarly timely manner, Burns’s participation could not be viewed as extraordinary.5 The court’s premise, therefore, excluded Burns from the ranks of the most extraordinarily timely defendants, while it remained silent regarding how his individual timeliness compares to that of the remainder of cooperating defendants, resulting in an overvaluation of his timeliness. Furthermore, we have previously reversed extraordinary departures under conditions of comparable timeliness where such timeliness did not yield a discernibly beneficial result. See Saenz, 428 F.3d at 1162-63 (noting that the timeliness of the defendant’s full cooperation did not, in and of itself, compel anyone else to plead guilty).
For similar reasons, we cannot agree with the district court that the truthfulness and completeness of Burns’s assistance constitutes a circumstance warranting a 60 percent departure under § 5Kl.l(a)(2). The safety-valve provision of § 501.2(a)(5) of the Sentencing Guidelines provides a sentencing reduction for a defendant who, by the time of sentencing, “has truthfully provided to the Government all information and evidence the defendant has concerning the offense or offenses.... ” U.S.S.G. § 501.2(a)(5). This guidelines section, and the underlying statute, 18 U.S.C. § 3553(f), permit relief from mandatory minimum sentences so long as the defendant provides the government all information that he has, regardless of its usefulness. Given the frequency with which defendants provide honest and complete assistance in compliance with § 501.2(a)(5) or with the hope that the government will enable an increased departure by making a § 5K1.1 or § 3553(e) motion, Burns’s honesty and the completeness of his assistance can hardly be viewed as so exceptional as to merit the reduction he received.6 We are skeptical whether complete truthfulness could ever warrant a departure of this magnitude in a substantial-assistance context — even where the defendant could not have offered more complete or more honest assistance. See Saenz, 428 F.3d at 1163 (“we respectfully disagree with the ... view that a strong showing in [timeliness and completeness] makes reasonable an extraordinary departure or reduction of more than 50 percent, or the equivalent of more than about eight offense levels for this defendant, without regard to the nature and extent of the defendant’s assistance, the significance and usefulness of the assistance, or any danger or risk of injury suffered by the cooperating defendant.”). Accordingly, although Burns’s honesty and completeness might *765help to justify a more favorable departure than that recommended by the government, the district court abused its discretion by according that factor the undue weight that it did.
The district court also supported its departure on the basis of an improper analysis of the “nature and extent” factor— § 5Kl.l(a)(3). It applied a test that compared Burns’s assistance to the assistance it speculatively believed the defendant capable of providing. Such a test invites sentencing disparities in contravention to the Sentencing Guidelines’s stated “goal [of] ‘reducing] unjustified disparities^ thereby] reaching] toward the even-handedness and neutrality that are the distinguishing marks of any principled system of justice.’ ” United States v. Petersen, 276 F.3d 432, 439 (8th Cir.2002) (quoting Koon v. United States, 518 U.S. 81, 113, 116 S.Ct. 2035, 135 L.Ed.2d 392 (1996)). Under the district court’s test, two defendants providing objectively identical assistance might well receive different departures based entirely on the respective judge’s speculative conjectures. Just as “the proper analysis under § 5Kl.l(a)(l) focuses on the actual significance and usefulness of the assistance, regardless of the defendant’s desire, effort, or ‘faulty’ ” Saenz, 428 F.3d at 1163-64, the proper analysis under § 5Kl.l(a)(3) focuses on the nature and extent of the actual, discrete, and specific activities constituting the assistance, regardless of the opportunities available or the defendant’s willingness and ability to provide more. Cf. United States v. Mills, 329 F.3d 24, 34 (1st Cir.2003) (upholding the district court’s recognition of only the defendant’s activities in focusing on the nature and extent of the defendant’s assistance). Among the § 5Kl.l(a) factors, the “nature and extent” and “significance and usefulness” considerations are particularly noteworthy for their inclusion of a broad spectrum of conduct. See U.S.S.G. § 5K1.1, cmt. background (isolating the two factors based on their breadth). Accordingly, even though Burns appeared before two grand juries, any departure granted to him premised on this factor must allow room for more substantial and extensive assistance. See Saenz, 428 F.3d at 1163 (implying that any combination of listed activities set forth as examples would represent more substantial and extensive assistance than the cooperation present). While the nature and extent of Burns’s assistance was not inconsiderable, it did not qualitatively justify the reduction awarded.
We conclude, then, that the departure exceeded that which was justified by the circumstances.7 The district court did not merely reduce the sentence by, say, 20 *766or 30 percent, but by 60 percent. This equated to a reduction of not, say, three to five offense levels, but ten levels. Given the sizeable qualitative difference between the totality of the assistance provided by Burns and that provided by Pizano, to uphold a reduction so far removed from the presumptively reasonable guidelines range would frustrate our goal of preventing departures from becoming untethered from the structure of the guidelines and would not reflect any meaningful sense of proportionality. As was the case in Coyle, there is also here “a good deal of room between the government’s modest recommendation and the district court’s generous departure to recognize this defendant’s assistance without at the same time skewing the degree of reduction that must be granted to future defendants whose performance on the continuum of substantial assistance deserves more credit than [Burns’s].” Coyle, 429 F.3d at 1194.
B.
Finally, we reject Burns’s contention on cross-appeal that the district court departed from the wrong guidelines range. Even though Burns acknowledges that he was subject to a mandatory life sentence, he contends that the government’s filing of a substantial assistance motion “waived” the mandatory life sentence, leaving the district court with a sentencing range of 188 to 235 months from which to depart. We do not agree. As the panel opinion held, the government’s substantial assistance motion did no more than permit the district court to sentence below the mandatory life sentence and did not negate the § 851 enhancement that made Burns eligible for a life sentence. Burns, 438 F.3d at 831. Accordingly, the district court properly departed from a presumptive life sentence of 360 months.8
The sentence is vacated, and the case is remanded to the district court for resen-tencing consistent with the views set forth in this opinion.
. We observe that, following Rita v. United States, - U.S. -, 127 S.Ct. 2456, 2465, 168 L.Ed.2d 203 (2007), the presumption of reasonableness for a sentence within a properly calculated guidelines range exists only at the appellate level.
. Even though a similar analysis has thus far been used to weigh the reasonableness of substantial assistance departures and of post-Booker variances, we do not mean to suggest through our citations to both types of sentencing cases that the substantial assistance departure standard should always, going forward, mirror the variance standard. Because post -Booker variances must be reasonable with regard to § 3553(a), while substantial-assistance reductions are considered under the rubric of the sentencing guidelines or of § 3553(e) (which itself is not affected by *762Booker, see United States v. Williams, 474 F.3d 1130, 1132 (8th Cir.2007)), the general analytical approaches and associated standards may diverge. We do not now consider whether the analysis should diverge. Nevertheless, we emphasize here that the present case is entirely a substantial assistance departure case.
. Instead of relying on aggregate statistics, when there is any uncertainty concerning the strength of circumstances required to justify a given departure level, the strength of the particularized circumstances present in, or required by, prior decisions dealing with comparable departures should be given controlling weight.
. Accordingly, our observation that extraordinary departures require extraordinary circumstances should be read to represent a shorthand for a generally applicable proportionality principle despite the fact that the literal terminology involved may facially appear limited to the largest of departures.
. There is reason to believe this is the case. The district court's conclusion fails to consider the government’s unaddressed and uncon- ■ tested insistence that many defendants cooperate in a similarly timely fashion.
. The government also alleges that the district court abused its discretion by adhering to its bright-line rule of granting a 50 percent minimum departure for any defendant supplying entirely truthful, complete, and reliable assistance. In Saenz, we rejected this bright-line rule in part because to allow it would deter the government from moving for sentence reductions in otherwise borderline assistance cases. Saenz, 428 F.3d at 1163. Although the district court did not mention the 50 percent departure rule at Burns’s sentencing hearing, we cannot say with certainty that the rule did not affect the district court’s thinking. Accordingly, we restate here our conclusion in Saenz that any reliance on the bright-line rule would also amount to an abuse of discretion.
. In reaching this conclusion, we have considered and find to be without merit the government's allegation that the district court failed to give substantial weight to the government’s evaluation. The commentary to § 5K1.1 requires that "substantial weight" be given to the government's evaluation of the extent of the assistance. U.S.S.G. § 5K1.1 cmt. n. 3. The government’s recommendation is not controlling, however, and it is the district court's responsibility to determine an appropriate reduction. Haack, 403 F.3d at 1005. Although the district court stated that "it's hard to put any weight on the 15 percent [recommendation of the government],” we conclude that the court overcame its reluctance and accorded the government's evaluation substantial weight, for the court ultimately justified its departure by citing the strength of factors other than § 5K1. 1(a)(1) despite its stated inclination to weigh the significance of Burns’s assistance heavily in his favor. Furthermore, the district court's comments indicate that it fully considered that which it could make out of the government's evaluation. Cf. Haack, 403 F.3d at 1005 n. 2 (stating that opaque government recommendations deserve less weight). We do not consider final departures substantially at variance with unexplained government recommendations to be de facto proof of discretionary abuse.
. We note that prior panels have held that it was not erroneous for district courts to use starting points in excess of 360 months when departing from life sentences. See, e.g., United States v. Keller, 413 F.3d 706, 711 (8th Cir.) (470 months), cert. denied, 546 U.S. 1053, 126 S.Ct. 786, 163 L.Ed.2d 609 (2005); United States v. Selby, 184 Fed.Appx. 589, 591 (8th Cir.2006) (unpublished per curiam) (405 months); see also United States v. Jensen, 493 F.3d 997, 1000-02 (8th Cir.2007) (expressing doubt about the adequacy of a 360-month starting point). Because the government has not appealed the 360-month starting point, we do not address the appropriateness of departing from a presumptive life sentence at, or in excess of, 360 months.