Kendrix D. Feemster was convicted of two counts of knowingly and intentionally distributing crack cocaine, in violation of 21 U.S.C. §§ 841(a)(1) and (b)(l)(B)(iii). At sentencing, the district court1 imposed the statutory mandatory minimum sentence of 120 months’ imprisonment and eight years of supervised release — a downward variance from the Guidelines range of 360 months’ to life. The government appealed the sentence, and we remanded for resentencing because the record did not permit us to meaningfully analyze the reasonableness of Feemster’s sentence. United States v. Feemster, 435 F.3d 881, 884 (8th Cir.2006) (“Feemster I ”). On remand, the district court again sentenced Feemster to 120 months’ imprisonment *458but buttressed the rationale for the sentence. The government again appealed, and we found that the district court abused its discretion. United, States v. Feemster, 483 F.3d 583, 588-90 (8th Cir.2007) (“Feemster II ”). The Supreme Court vacated the judgment and remanded to us for further consideration in light of Gall v. United States, 552 U.S. 38, 128 S.Ct. 586, 169 L.Ed.2d 445 (2007). We now affirm.
I. Background
On March 16, 2004, Feemster sold 11.2 grams of crack cocaine to an undercover Drug Enforcement Administration (DEA) agent. Then, on March 25, 2004, he sold 6.8 grams of crack cocaine to the same officer. Thereafter, a grand jury charged Feemster with two counts of knowingly and intentionally distributing crack cocaine, in violation of 21 U.S.C. §§ 841(a)(1) and (b)(l)(B)(iii).2 Prior to trial, the government filed an information pursuant to 21 U.S.C. § 851(a) giving notice that, if convicted, Feemster faced a ten-year mandatory minimum sentence because of his prior conviction for a felony drug offense. Feemster went to trial, and the jury convicted him on both counts.
Prior to sentencing, the United States Probation Office prepared a presentence investigation report (PSR) that set forth Feemster’s criminal history. According to the undisputed sections of the PSR,3 Feemster had the following juvenile convictions: (1) at age 13, attempted stealing; (2) at age 14, making a false bomb report; and (3) at age 15, stealing, attempted steal-
ing, and second-degree burglary. Additionally, Feemster had the following adult convictions and sentences: (1) at age 16, possession of a controlled substance (crack cocaine) and possession of marijuana, resulting in a suspended sentence and probation, which he successfully completed; (2) at age 17, first-degree burglary, resulting in a sentence of six years’ imprisonment (including citations for conduct violations on 65 separate occasions), from which he was twice conditionally released and both times his conditional release was revoked (submitting a positive urine test for marijuana); (3) at age 23, first-degree robbery (involving a handgun carried by his co-defendant), resulting in a ten-year suspended sentence and probation, which he violated; and (4) at age 24, possession of marijuana, resulting in a 60-day suspended sentence and one-year unsupervised probation.
Without enhancements, Feemster’s base offense level was 26, see U.S.S.G. § 2D1.1(c)(7), and his criminal history category was IV, resulting in an advisory Guidelines range of 92 to 115 months’ imprisonment. Feemster’s prior conviction for a felony drug offense triggered a statutory minimum sentence of 120 months’ imprisonment. See 21 U.S.C. §§ 841(b)(1)(B), 851. Also, Feemster’s adult status at the time he committed the instant offense and his prior convictions for two crimes of violence — first-degree burglary and first-degree robbery— prompted the probation office to recommend application of the career offender *459enhancement in the PSR. See U.S.S.G. § 4Bl.l(a) (“A defendant is a career offender if (1) the defendant was at least eighteen years old at the time the defendant committed the instant offense of conviction; (2) the instant offense of conviction is a felony that is either a crime of violence or a controlled substance offense; and (3) the defendant has at least two prior felony convictions of either a crime of violence or a controlled substance offense.”). The career offender enhancement set Feemster’s offense level at 37 and his criminal history category at VI, yielding an advisory Guidelines range of 360 months to life imprisonment.
At sentencing on March 10, 2005, Feemster requested that the district court consider a sentence lower than his Guidelines range, reminding the court that, absent his two qualifying crimes of violence, he would be facing a sentencing range of 92 to 115 months’ imprisonment. The district court acknowledged that Feemster committed one of these crimes at age 17 and the other at age 23. Additionally, the court noted that Feemster’s sentencing range had already increased from 92 to 115 months to at least 120 months by virtue of the mandatory minimum. The government argued that a 30-year Guidelines sentence was reasonable given Feemster’s criminal history. But the court disagreed, stating:
I think this sentence is too much. 360 is too much because the offense you’re counting on [for application of the ten-year mandatory minimum] is this 16-year-old drug offense for one when he was 16 years old. He’s only 24. The crimes of alleged violence were one at 17, burglary, and the other at 23, the robbery.
The comí then sentenced Feemster to concurrent 120-month sentences on each count of conviction, to be followed by three years of supervised release. On March 17, 2005, Feemster was brought before the court to correct the term of supervised release so that it met the statutory minimum of eight years. At the hearing, the court reiterated its reasons for deviating from the Guidelines range, explaining:
And I know that there was some inquiry relative to Mr. Feemster’s sentence of 120 months, and I sentenced him there because in considering the defendant’s age, current age and age at which he committed the prior offenses including offense when he was 17-16 and 17 years old, and that’s why I gave him that sentence that he received.
The government appealed, and we remanded to the district court for resentencing, concluding that “the record at this time does not permit our court to undertake a meaningful analysis of whether the sentence imposed is unreasonable.” Feemster 1, 435 F.3d at 884.
At resentencing, the district court further developed its reasoning for sentencing Feemster to 120 months’ imprisonment, stating:
Now, at the time that Mr. Feemster was sentenced!,] he was 27. At the time of the offense, ... he was 26.... Now, it’s unquestioned that Mr. Feemster was a troubled youth. As they say, “Youth is wasted on the young.” They just need a little wisdom. When he started getting ... these points!,] ... he was 17 years old.
In any event, [t]he [c]ourt has looked at the 3553(a) factors and at the time the instant offense was committed the defendant was 26 years of age, it involved the distribution of 18 grams of cocaine base to a federal agent. No weapon was present. And while the defendant does have a record and much of it is significant because of his being a troubled youth, it would seem it includes violent felony convictions, and that’s what made *460him a career offender, and many — most of those ... prior convictions occurred when he was a juvenile.
Now, as [sic] his adult conviction[,] he’s placed on probation. He successfully completed that. Now, his second adult conviction involved the burglary of a home. And his third adult conviction was for robbery first degree which involved a weapon. However, his codefendant, Dean Goddard, who had the weapon and defendant did not. And his fourth and final conviction was a misdemeanor for possession of marijuana. He was placed on probation. He successfully completed that probation.
So to me I think this 360 months to life is excessive. I think it pretty much takes away Mr. Feemster’s life, so ... in light of these 3553(a) factors, so I think an aggregate term of 120 months to be served concurrently with his state sentence of 1 CR-2495A and eight years of supervised release would seem to address the sentencing objectives of punishment and deterrence and incapacitation. I think ... ten years and then eight years of supervised release, I think ... that’s 18 years right there that he will be under some kind of supervision by the court system.
The government appealed, and this court again remanded, finding that the district court abused its discretion by: (1) giving too much weight to Feemster’s young age at the time of his prior offenses; (2) substantially basing the variance on Feemster’s age at the time of the instant offense and sentencing; (3) considering Feemster’s lack of involvement with firearms, when such lack of involvement had already been accounted for in calculating Feemster’s Guidelines range; and (4) considering Feemster’s successful completion of two terms of probation, when failure to complete his probation would have warranted further punishment. Feemster II, 483 F.3d at 588-90. The Supreme Court vacated the judgment and remanded for further consideration in light of Gall.
II. Discussion
According to the government, Feemster’s 120-month sentence is procedurally unreasonable because the district court failed to provide an adequate explanation for the chosen sentence. In the alternative, the government argues that Feemster’s sentence is substantively unreasonable for a defendant who has a lengthy and serious criminal history and who has not shown that prior sentences have deterred him from criminal activity.
In response, Feemster argues that the Supreme Court’s decisions in Gall and Kimbrough v. United States, 552 U.S. 85, 128 S.Ct. 558, 169 L.Ed.2d 481 (2007), establish a deferential standard of review for district court criminal sentencing decisions. According to Feemster, while an appellate court may still consider the extent of the district court’s deviation from the Guidelines range, it must give due deference to the district court’s determination that the § 3553(a) factors, on a whole, justify the extent of the variance. Feemster asserts that the district court committed no procedural error in formulating his sentence, as it correctly calculated the advisory Guidelines range, treated the Guidelines as advisory, considered all of the § 3553(a) factors, did not utilize any clearly erroneous facts, and adequately explained its reasoning for the sentence imposed. He also asserts that his sentence is substantively reasonable and that, even if this court would have imposed a different sentence, it must still give due deference to the district court’s individualized decision.
“[A] district court should begin all sentencing proceedings by correctly cal*461culating the applicable Guidelines range.” Gall, 128 S.Ct. at 596. Then, after the court affords both parties an opportunity to argue “for whatever sentence they deem appropriate,” it “should then consider all of the § 3553(a) factors to determine whether they support the sentence requested by a party.” Id. In making this determination, the district court is prohibited from presuming that the Guidelines range is reasonable. Id. Instead, it must “make an individualized assessment based on the facts presented.” Id. If the court concludes that a sentence outside of the Guidelines range is warranted, then it must “consider the extent of the deviation and ensure that the justification is sufficiently compelling to support the degree of the variance.” Id. “[A] major departure should be supported by a more significant justification than a minor one.” Id. After the district court determines the “appropriate sentence,” it must then “adequately explain the chosen sentence to allow for meaningful appellate review and to promote the perception of fair sentencing.” Id.; see also id. at 594 (stating that, in fashioning a defendant’s sentence, the district court “must give serious consideration to the extent of any departure from the Guidelines and must explain his conclusion that an unusually lenient or an unusually harsh sentence is appropriate in a particular case with sufficient justifications”).
“When we review the imposition of sentences, whether inside or outside the Guidelines range, we apply ‘a deferential abuse-of-discretion standard.’ ” United States v. Hayes, 518 F.3d 989, 995 (8th Cir.2008) (quoting Gall, 128 S.Ct. at 591). We “must first ensure that the district court committed no significant procedural error.” Gall, 128 S.Ct. at 597. “Procedural error” includes “failing to calculate (or improperly calculating) the Guidelines range, treating the Guidelines as mandatory, failing to consider the § 3553(a) factors, selecting a sentence based on clearly erroneous facts, or failing to adequately explain the chosen sentence — including an explanation for any deviation from the Guidelines range.” Id.
A district court abuses its discretion when it (1) “fails to consider a relevant factor that should have received significant weight”; (2) “gives significant weight to an improper or irrelevant factor”; or (3) “considers only the appropriate factors but in weighing those factors commits a clear error of judgment.” United States v. Kane, 552 F.3d 748, 752 (8th Cir.2009) (internal quotations and citation omitted). In determining whether a district court committed procedural error, “[w]e do not require a district court to provide a mechanical recitation of the § 3553(a) factors when determining a sentence. Rather, it simply must be clear from the record that the district court actually considered the § 3553(a) factors in determining the sentence.” United States v. Walking Eagle, 553 F.3d 654, 659 (8th Cir.2009) (internal quotations and citation omitted).
In the absence of procedural error below, we “should then consider the substantive reasonableness of the sentence imposed under an abuse-of-discretion standard.” Gall, 128 S.Ct. at 597. In conducting this review, we are to “take into account the totality of the circumstances, including the extent of any variance from the Guidelines range.” Id. If the defendant’s sentence is within the Guidelines range, then we “may, but [are] not required to, apply a presumption of reasonableness.” Id. But we are not permitted to apply a presumption of unreasonableness if the sentence is outside the Guidelines range. Id. Instead, we “may consider the extent of the deviation, but must give due deference to the district court’s *462decision that the § 3553(a) factors, on a whole, justify the extent of the variance.” Id. We may not require “ ‘extraordinary’ circumstances to justify a sentence outside the Guidelines” and are prohibited from “the use of a rigid mathematical formula that uses the percentage of a departure as the standard for determining the strength of the justifications required for a specific sentence.” Id. at 595. Just because we “might reasonably have concluded that a different sentence was appropriate is insufficient to justify reversal of the district court.” Id. at 597.
Post-GaZZ, appellate courts have begun to make their way across the new legal landscape of abuse-of-discretion sentence review. Like our sister circuits, we are endeavoring to determine what constitutes an abuse of discretion by a district court in sentencing a defendant outside of the Guidelines range. The Court in Gall expressly prohibited appellate courts from employing “rigid mathematical formulas” and an “extraordinary circumstances” test when reviewing the reasonableness of a sentence. Id. at 595. But the Court also expressly permitted appellate courts to “consider the extent of the deviation” from the Guidelines. Id. at 597. Additionally, the Court required that a district court “give serious consideration to the extent of any departure from the Guidelines and must explain [its] conclusion that an unusually lenient or an unusually harsh sen-fence is appropriate in a particular case with sufficient justifications.” Id. at 594. The parameters of these unusual deviations certainly have not been surveyed and mapped.4
Here, the government argues that the district court committed procedural error and should be reversed. The government relies solely on its allegation that the court failed to provide an “adequate explanation” for imposing a 120-month sentence, but it specifically disclaims any argument that the district court considered irrelevant factors in fashioning the sentence. Appellant’s Supplemental Brief at 9, 12. According to the government, factors such as “Feemster’s age at the time of the instant offense, the absence of a weapon in the instant offense, and Feemster’s allegedly ‘successful completion’ ... of the terms of probation for some of his prior offenses” are factors that “appear to fall within the extremely broad ambit of Section 3553(a), which includes ‘the nature and circumstances of the offense and the history and characteristics of the defendant.’ ” Id. at 12 (quoting 18 U.S.C. § 3553(a)(1)). Furthermore, the government concedes that “because the various sentencing considerations set forth in Section 3553(a) overlap to a considerable degree, a fact that is already taken into account in the computation of a defendant’s advisory Sentencing Guidelines range ... may also be relevant to other subsections of Section 3553(a).” *463Id. at 12-13. As a result, the government acknowledges that the district court could properly “consider the absence of a weapon as a circumstance of the offense under Section 3553(a)(1), even if the absence of a weapon also affects the defendant’s Guidelines range.” Id. at 13.
Given these concessions, we will restrict our review to whether the district court adequately explained its chosen sentence. According to the government, the district court’s sentence is “procedurally unreasonable for want of an adequate explanation” because
despite Feemster’s prior convictions for crimes of violence and his multitude of lesser violations, citations, and arrests, the district court sentenced Feemster in 2006 to the same statutory mandatory minimum that the court would have been required to impose had Feemster been a model citizen during the interval between Feemster’s first felony cocaine base conviction and his conviction in the present case. Under those circumstances, the district court’s abrupt announcement of a 120-month sentence, along with its unadorned statement that the Guidelines range of “360 months to life is excessive” ... is procedurally unreasonable for want of an adequate explanation.
Id. at 17-18.5
We. disagree. The record reflects that the district court provided, as our precedent requires, substantial “insight into the reasons for its determination.” Kane, 552 F.3d at 756 (finding that, apart from one comment, the court failed to provide additional insight into the reasons for imposing a 90-month downward variance). Applying the § 3553(a) factors, the district court offered three justifications for the variance. First, the court noted Feemster’s youth, as it observed that Feemster’s criminal career began at age 17. Second, the court observed that apparently no weapon was present at the time Feemster committed the instant offense. Third, the court cited Feemster’s successful completion of probation. The government has already conceded that these justifications are “relevant factors.” In combination, they form an adequate explanation for why the district court determined that “360 months to life is excessive.” Furthermore, the district court acknowledged that it had considered the § 3553(a) factors before imposing a sentence of 120 months’ imprisonment.
The district court did not turn a blind eye to the defendant’s conduct but ac*464knowledged Feemster’s “record” and “violent felony convictions.” Cf. United States v. Shy, 538 F.3d 933, 937 (8th Cir.2008) (holding that, in sentencing defendant who pleaded guilty to possession of pseudoephedrine with knowledge that it would be used to manufacture methamphetamine, the district court failed to adequately explain the defendant’s sentence because it did not discuss the “critical fact” that the defendant possessed methamphetamine when she was arrested, which undermined the court’s conclusion that the defendant was “no longer the same person who committed the crime two years earlier and was capable of cleaning up her act and avoiding criminal conduct in the future”). Instead, the district court, acting within its discretion and applying the § 3553(a) factors, was not unreasonable in concluding that its three enunciated justifications supported a sentence of 120 months’ imprisonment.
With regard to substantive reasonableness under § 3553(a), we agree with the D.C. Circuit that because the Guidelines are now advisory only, “substantive appellate review in sentencing cases is narrow and deferential. As the case law in the courts of appeals since Gall demonstrates, it will be the unusual case when we reverse a district court sentence — whether within, above, or below the applicable Guidelines range — as substantively unreasonable.” United States v. Gardellini, 545 F.3d 1089, 1090 (D.C.Cir. 2008). Here, the district court’s justifications for imposing a 120-month sentence “rest[ ] on precisely the kind of defendant-specific determinations that are within the special competence of sentencing courts, as the Supreme Court has repeatedly emphasized.” Id. at 1095. As a result, we cannot say that the district court abused its discretion in sentencing Feemster to 120 months’ imprisonment.
III. Conclusion
Accordingly, we affirm the judgment of the district court.
. The Honorable Charles A. Shaw, United States District Judge for the Eastern District of Missouri.
. Although Feemster was originally charged with three counts, the district court dismissed one count, based on a March 11, 2004 sale of 5.7 grams of crack cocaine to an undercover DEA agent, on the government’s motion to protect the confidentiality of one of its informants.
. Because Feemster did not object to the PSR’s specific factual allegations, we accept as true the facts set forth in the PSR. See United States v. Jenners, 473 F.3d 894, 897 (8th Cir.2007) (stating that although ''[a] PSR is not evidence,” a district court is permitted to accept the facts in the PSR as true unless the defendant files an objection to specific factual allegations).
. The Third Circuit recently expressed its frustration with the current sentencing regime, stating: "We do not pretend that the foregoing observations provide much, if any, guidance. Indeed, we find it difficult to give direction when we are ourselves endeavoring to understand our role in reviewing sentences after Booker, Rita, Gall, and Kimbrough.” United States v. Levinson, 543 F.3d 190, 197 (3d Cir.2008). The court then gave an example of the "mixed messages that can be drawn from Gall,” explaining:
On the one hand, we are told that proportionality between the extent of a variance and the extent of the justification for the variance is not required, 128 S.Ct. at 595 (rejecting an approach "that uses the percentage of a departure as the standard for determining the strength of the justifications required for a specific sentence”), while, on the other hand, we are advised that a major variance “should be supported by a more significant justification than a minor one,” id. at 597.
Id. at 197 n. 6.
. Additionally, the government notes that, although the district court "found that Feemster had successfully completed two terms of probation, the record does not reveal that Feemster successfully completed either term.” Id. at 16. While the government has conceded that it is only challenging the adequacy of the district court’s explanation, this argument seems to challenge the district court's factual findings. Nevertheless, we find that the district court’s findings that Feemster successfully completed probation on his first adult conviction and his “fourth and final conviction” for "misdemeanor for possession of marijuana” are supported by the PSR. Paragraph 46 of the PSR states that Feemster was placed on probation for possession of a controlled substance (crack cocaine) and possession of marijuana. Paragraph 49 states that "[c]ourt records do not reflect any probation violations.” As to Feemster’s fourth conviction for possession of marijuana, ¶ 59 of the PSR states that he was “placed on probation for one year.” Paragraph 62 states that "[¡Information regarding probation adjustment is unavailable because the probation was unsupervised.” Although ¶ 62 does not definitively state that Feemster successfully completed this probation, the government presented no evidence that he did not. Thus, the district court was permitted to draw the inference that Feemster successfully completed his probation.