This appeal represents a lawyer’s nightmare. A sophisticated law firm, with what it thought was a sophisticated system to determine and calendar filing deadlines, missed a critical one: the 30-day time period in which to file a notice of appeal under Federal Rule of Appellate Procedure 4(a)(1)(A). The rule, however, provides for a grace period of 30 days within which a lawyer in such a fix may ask the district court for an extension of time, and the court, in the exercise of its discretion, may grant the extension if it determines that the neglect of the attorney was “excusable.”1 Here an experienced trial judge found excusable neglect, and the appellee asks us to overturn that ruling.
The underlying dispute began in 1989 when Laffit Pincay, Jr. and Christopher MeCarron (Pincay) sued Vincent S. Andrews, Robert L. Andrews, and Vincent Andrews Management Corp. (Andrews) for financial injuries stemming from alleged violations of the Racketeer Influenced and Corrupt Organizations Act (RICO) and California law. In 1992, a jury returned verdicts in Pincay’s favor on both the RICO and the California counts. Pincay was ordered to elect a remedy, and *855he chose to pursue the RICO judgment. This judgment was reversed on appeal on the ground that the RICO claim was barred by the federal statute of limitations. Pincay v. Andrews, 238 F.3d 1106, 1110 (9th Cir.2001). On remand, Pincay elected to pursue the remedy on his California law claim. Judgment was entered in his favor on July 3, 2002.
Andrews’s notice of appeal was due 30 days later, but a paralegal charged with calendaring filing deadlines misread the rule and advised Andrews’s attorney that the notice was not due for 60 days, the time allowed when the government is a party to the case. See Fed. R.App. P. 4(a)(1)(B). Andrews’s counsel learned about the error when Pincay relied upon the judgment as being final in related bankruptcy proceedings, and Andrews promptly tendered a notice of appeal together with a request for an extension within the 30-day grace period. By that time the matter had been in litigation for more than 15 years. Everyone involved should have been well aware that the government was not a party to the case, and any lawyer or paralegal should have been able to read the rule correctly. The misreading of the rule was a critical error that, had the district court viewed the situation differently, would have ended the litigation then and there with an irreparably adverse result for Andrews. The district court, however, found the neglect excusable and granted the motion for an extension of time to file the notice of appeal.
Pincay appealed to this court, and a majority of the three-judge panel concluded that Andrews’s attorney had improperly delegated the function of calendaring to a paralegal, and held that the attorney’s reliance on a paralegal was inexcusable as a matter of law. Pincay v. Andrews, 351 F.3d 947, 951-52 (9th Cir.2003). It ordered the appeal dismissed. The dissent would have applied a more flexible and deferential standard and affirmed the district court. Id. at 952-56 (Kleinfeld, J., dissenting).
A majority of the active non-recused judges of the court voted to rehear the case en banc to consider whether the creation of a per se rule against delegation to paralegals, or indeed any per se rule involving missed filing deadlines, is consistent with the United States Supreme Court’s leading authority on the modern concept of excusable neglect, Pioneer Investment Services Co. v. Brunswick Associates Ltd. Partnership, 507 U.S. 380, 113 S.Ct. 1489, 123 L.Ed.2d 74 (1993). We now hold that per se rules are not consistent with Pioneer, and we uphold the exercise of the district court’s discretion to permit the filing of the notice of appeal in this case.
The Pioneer decision arose in the bankruptcy context and involved the “bar date” for the filing of claims. The Court in Pioneer established a four-part balancing test for determining whether there had been “excusable neglect” within the meaning of Federal Rule of Bankruptcy Procedure 9006(b)(1). The Court also reviewed various contexts in which the phrase appeared in the federal rules of procedure and made it clear the same test applies in all those contexts. The Pioneer factors include: (1) the danger of prejudice to the non-moving party, (2) the length of delay and its potential impact on judicial proceedings, (3) the reason for the delay, including whether it was within the reasonable control of the movant, and (4) whether the moving party’s conduct was in good faith. 507 U.S. at 395, 113 S.Ct. 1489.
In this case, the district court analyzed each of the Pioneer factors and correctly found: (1) there was no prejudice, (2) the length of delay was small, (3) the reason *856for the delay was carelessness, and (4) there was no evidence of bad faith. It then concluded that even though the reason for the delay was the carelessness of Andrews’s counsel, that fact did not render the neglect inexcusable. The district court relied on this court’s decision in Marx v. Loral Corp., 87 F.3d 1049 (9th Cir.1996), in which we affirmed an order granting an extension of time in a case that involved an attorney’s calendaring error.
Because the panel majority decided the case in part on the issue of delegation of calendaring to a paralegal, we consider that issue first. This issue was not presented to the district court, and it was raised sua sponte by the three-judge panel.
In the modern world of legal practice, the delegation of repetitive legal tasks to paralegals has become a necessary fixture. Such delegation has become an integral part of the struggle to keep down the costs of legal representation. Moreover, the delegation of such tasks to specialized, well-educated non-lawyers may well ensure greater accuracy in meeting deadlines than a practice of having each lawyer in a large firm calculate each filing deadline anew. The task of keeping track of necessary deadlines will involve some delegation. The responsibility for the error falls on the attorney regardless of whether the error was made by an attorney or a paralegal. See Model Rules of Prof 1 Conduct R. 5.5 cmt. 2 (2002) (“This Rule does not prohibit a lawyer from employing the services of paraprofessionals and delegating functions to them, so long as the lawyer supervises the delegated work and retains responsibility for their work.”). We hold that delegation of the task of ascertaining the deadline was not per se inexcusable neglect.
The larger question in this case is whether the misreading of the clear rule could appropriately have been considered excusable. Resolution of that question requires some effort to try to distill any principles that have evolved in the 10 years since Pioneer. In Pioneer itself, the Court adopted a broader and more flexible test for excusable neglect. A narrower test existed in many circuits before Pioneer that limited excusable neglect to situations that were beyond the control of the movant for an extension as, for example, the messenger being hit by a truck on the way to the court clerk’s filing desk. See Pioneer, 507 U.S. at 387-88 & n. 3, 113 S.Ct. 1489.
The district court followed our decision in Marx, where we acknowledged that Pioneer had worked a change in our circuit’s law as to what constitutes excusable neglect. 87 F.3d at 1053-54. As we explained in Marx, our “strict standard,” which required both a showing of extraordinary circumstances that prevented timely filing and injustice resulting from denying an extension, id. at 1053 (citing Pratt v. McCarthy, 850 F.2d 590, 593 (9th Cir.1988)), gave way to an equitable determination that involves consideration of the four Pioneer factors. Id. at 1054. We therefore affirmed the district court’s grant of an extension of time to file a notice of appeal in Marx because the district court correctly considered the Pioneer factors. We found that the district court did not abuse its discretion, and we said: “The district court’s analysis of the Pioneer Inv. factors in this case, although considerably lenient to the plaintiffs, was not a clear error of judgment.” Id.
Our court, in other cases, has also described Pioneer’s, flexible approach, saying, for example, “we will ordinarily examine all of the circumstances involved rather than holding that any single circumstance in isolation compels a particular result regardless of the other factors.” Briones v. *857Riviera Hotel & Casino, 116 F.3d 379, 382 n. 2 (9th Cir.1997); see also Bateman v. United States Postal Serv., 231 F.3d 1220, 1224 (9th Cir.2000).
We seemed to take a more narrow approach in Kyle v. Campbell Soup Co., 28 F.3d 928 (9th Cir.1994). In that case our court reversed the district court’s finding of excusable neglect. We emphasized the fact that the attorney had made a mistake in interpreting rules that were not ambiguous and we focused on the particular facts of Pioneer, including a “dramatic ambiguity” in the notice of the filing deadline at issue. Id. at 931.
Our circuit’s confusion is not isolated. The authorities interpreting Pioneer in a number of circuits are in some disarray. In fact, the confusion begins with Pioneer itself, and various subsequent circuit opinions have cited similar portions of Pioneer to support their respective but differing conclusions. The key passage in Pioneer, having a little something for everyone, is as follows:
Although inadvertence, ignorance of the rules, or mistakes construing the rules do not usually constitute “excusable” neglect, it is clear that “Dexeusable neglect” under [Bankruptcy] Rule 6(b) is a some-what “elastic concept” and is not limited strictly to omissions caused by circumstances beyond the control of the movant.
507 U.S. at 392, 113 S.Ct. 1489 (internal footnotes omitted).
The experience of the Seventh and Fifth Circuits is instructive. The Seventh Circuit in Prizevoits v. Indiana Bell Telephone Co., 76 F.3d 132 (7th Cir.1996), dismissed an appeal for lack of jurisdiction because the notice was not filed within the 30 days required by the Rule. In that case the attorney had missed the deadline for filing a motion under Federal Rule of Civil Procedure 59(e) to alter or amend the judgment and filed a motion to extend the time. The district court denied this motion because no extension is allowed under Rule 59. The time for filing a notice of appeal expired, however, while the motion was pending before the district court, and so the attorney moved for an extension under Rule 4. The district court granted the extension of time to appeal, but the Seventh Circuit reversed. Id. at 133. The Prizevoits majority cited Pioneer for the proposition that “excusable neglect’ is not limited to situations where the failure to timely file ‘is due to circumstances beyond the control of the filer,’ ” id. at 134 (quoting Pioneer, 507 U.S. at 391, 113 S.Ct. 1489), but limited the reach of Pioneer to such things as “plausible misinterpretations of ambiguous rules.” Id. The majority then concluded: “Here the rule is crystal clear, the error egregious, the excuses so thin as to leave the lapse not only unexcused but inexplicable. If there was ‘excusable’ neglect here, we have difficulty imagining a case of inexcusable neglect.” Id.
Judge Eschbach’s dissent also relied on Pioneer and criticized the majority’s choice “not to address the impact of Pioneer on our past decisions.” Id. at 136. The dissent said: “In Pioneer, the Court held that attorney negligence may, in certain circumstances, constitute ‘excusable neglect,’ considerably liberalizing its meaning and prescribing a new analytical test.” Id.
In the Fifth Circuit, a majority relied on Prizevoits in Midwest Employers Cas. Co. v. Williams, 161 F.3d 877 (5th Cir.1998), over a strong dissent by Judge Garza. Judge Garza cited authority, seemingly contrary to the majority, from both the Fifth and Seventh Circuits, interpreting the equitable factors of Pioneer. Id. at 882-84, 885. He cited United States v. Evbuomwan, 36 F.3d 89 (5th Cir.1994) (unpublished opinion) (reported at 36 F.3d *85889 (table case)),2 “where the court found that the district court did not abuse its discretion in finding that a good faith misinterpretation of plain rules was excusable neglect.” He also cited Lackey v. Atlantic Richfield Co., 990 F.2d 202, 205 (5th Cir.1993), where the court found that the district court did not abuse its discretion in finding excusable neglect because the attorney’s obvious error was mitigated by the lack of prejudice to the nonmovant and the shortness of the delay. Finally, he cited United States v. Brown, 133 F.3d 993 (7th Cir.1998), where the Seventh Circuit affirmed the district court’s finding that an attorney’s confusing of state rules with federal rules amounted to excusable neglect. Id. at 996. The Seventh Circuit said: “Pioneer made clear that the standard is a balancing test, meaning that a delay might be excused even where the reasons for the delay are not particularly compelling.” Id. at 997.
The Eleventh Circuit seems to have set forth a more categorical test. In Advanced Estimating System, Inc. v. Riney, 130 F.3d 996 (11th Cir.1997), the court stated: “The ancient legal maxim continues to apply: ignorance of fact may excuse; ignorance of law does not excuse. Accordingly, [Appellant’s] counsel’s misunderstanding of the law cannot constitute excusable neglect.” Id. at 999 (citations omitted). That decision seemed to move the Eleventh Circuit back toward the approach it had taken before Pioneer, and which Pioneer rejected, i.e., excusable neglect is limited to matters beyond the control of the attorney. See In re Analytical Systems, 933 F.2d 939, 942 (11th Cir.1991) (reciting the Eleventh Circuit’s pre-Pio-neer standard for establishing excusable neglect); Pioneer, 507 U.S. at 387 n. 3, 113 S.Ct. 1489 (citing In re Analytical Sys. as an example of a court that had taken a narrow view of excusable neglect). In Pioneer, the Supreme Court rejected “a bright-line ride of the sort embraced by some Courts of Appeals, erecting a rigid barrier against late filings attributable in any degree to the movant’s negligence” as “irreconcilable with our cases.” 507 U.S. at 395 n. 14, 113 S.Ct. 1489.
Despite this confusion, there appears to be general agreement on at least one principle: the standard of review. We review for abuse of discretion a district court’s decision to grant or deny a motion for an extension of time to file a notice of appeal. Marx, 87 F.3d at 1054; see also Pioneer, 507 U.S. at 398, 113 S.Ct. 1489 (“To be sure, were there any evidence of prejudice to petitioner or to judicial administration in this case, or any indication at all of bad faith, we could not say that the Bankruptcy Court abused its discretion in declining to find the neglect to be ‘excusable.’ ”); Kyle, 28 F.3d at 930; Silivanch v. Celebrity Cruises, Inc., 333 F.3d 355, 362 (2d Cir.2003); Midwest Employers Cas. Co., 161 F.3d at 879; Advanced Estimating Sys., 130 F.3d at 997. We must therefore affirm unless we are left with the definite and firm conviction that the lower court committed a clear error of judgment in the conclusion it reached after weighing the relevant factors. Marx, 87 F.3d at 1054.
In this case the mistake itself, the misreading of the Rule, was egregious, and the lawyer undoubtedly should have checked the Rule itself before relying on the paralegal’s reading. Both the paralegal and the lawyer were negligent. That, however, represents the beginning of our inquiry as to whether the negligence is *859excusable, not the end of it. The real question is whether there was enough in the context of this case to bring a determination of excusable neglect within the district court’s discretion.
We therefore turn to examining the Pioneer factors as they apply here. The parties seem to agree that three of the factors militate in favor of excusability, and they focus their arguments on the remaining factor: the reason for the delay. Appellee Andrews characterizes the reason for the delay as the failure of a “carefully designed” calendaring system operated by experienced paralegals that heretofore had worked flawlessly. Appellant Pincay, on the other hand, stresses the degree of carelessness in the failure to read the applicable Rule.
We recognize that a lawyer’s failure to read an applicable rule is one of the least compelling excuses that can be offered; yet the nature of the contextual analysis and the balancing of the factors adopted in Pioneer counsel against the creation of any rigid rule. Rather, the decision whether to grant or deny an extension of time to file a notice of appeal should be entrusted to the discretion of the district court because the district court is in a better position than we are to evaluate factors such as whether the lawyer had otherwise been diligent, the propensity of the other side to capitalize on petty mistakes, the quality of representation of the lawyers (in this litigation over its 15-year history), and the likelihood of injustice if the appeal was not allowed. Had the district court declined to permit the filing of the notice, we would be hard pressed to find any rationale requiring us to reverse.
Pioneer itself instructs courts to determine the issue of excusable neglect within the context of the particular case, a context with which the trial court is most familiar. Any rationale suggesting that misinterpretation of an unambiguous rule can never be excusable neglect is, in our view, contrary to that instruction. “[T]he right way, under Pioneer, to decide cases involving ignorance of federal rules is with an ‘elastic concept’ equitable in nature, not with a per se rule.” Pincay v. Andrews, 351 F.3d 947, 953 (9th Cir.2003) (Kleinfeld, J., dissenting).
We are also mindful that Rule 4 itself provides for leniency in limited circumstances. It could have been written more rigidly, allowing for no window of opportunity once the deadline was missed. Many states’ rules provide for an extension of the time for filing a notice of appeal under few, if any, circumstances. See, e.g., Ariz. R. Civ.App. P. 9 (providing for an extension of time to file a notice of appeal only if a party did not receive notice of the entry of judgment and no party would be prejudiced); Matter of Appeal in Pima County Juvenile Action No. S-933, 135 Ariz. 278, 660 P.2d 1205, 1207 (1982) (“Excusable neglect affords no basis for relief from the dismissal of an untimely appeal.”); Cal. R. Ct. 3 (listing circumstances in which the time to appeal is extended and not including an extension for excusable neglect); In re Hanley’s Estate, 23 Cal.2d 120, 142 P.2d 423, 424-25 (1943) (“In the absence of statutory authorization, neither the trial nor appellate courts may extend or shorten the time for appeal even to relieve against mistake, inadvertence, accident, or misfortune.”) (internal citations omitted). The federal rule is a more flexible one that permits a narrow 30-day window for requesting an extension, and the trial court has wide discretion as to whether to excuse the lapse.
We understand several of our sister circuits have tried to fashion a rule making a mistake of law per se inexcusable under Rule 4. See, e.g., Silivanch, 333 F.3d at 368-69 (quoting Weinstock v. Cleary, Gott*860lieb, Steen & Hamilton, 16 F.3d 501, 503 (2d Cir.1994), which in turn quotes a series of pre-Pioneer cases including In re Cosmopolitan Aviation Corp., 763 F.2d 507, 515 (2d Cir.1985)) (“‘[t]he excusable neglect standard can never be met by a showing of inability or refusal to read and comprehend the plain language -of the federal rules.’ ”); Advanced Estimating Sys., 130 F.3d at 998 (“[A]n attorney’s misunderstanding of the plain language of a rule cannot constitute excusable neglect.”). Prizevoits, 76 F.3d at 133 (“An unaccountable lapse is not excusable neglect.”); We agree that a lawyer’s mistake of law in reading a rule of procedure is not a compelling excuse. At the same time, however, a lawyer’s mistake of fact, for example, in thinking the government was a party to a case and that the 60-day rule applied for that reason, would be no more compelling.
We are persuaded that, under Pioneer, the correct approach is to avoid any per se rule. Pioneer cautioned against “erecting a rigid barrier against late filings attributable in any degree to the movant’s negligence.” 507 U.S. at 395 n. 14, 113 S.Ct. 1489. There should similarly be no rigid legal rule against late filings attributable to any particular type of negligence. Instead, we leave the weighing of Pioneer’s equitable factors to the discretion of the district court in every case.
We hold that the district court did not abuse its discretion in this case. Therefore, the district court’s order granting the defendant’s motion for an extension of time to file the notice of appeal is AFFIRMED. The merits of the appeal are before the three judge panel in appeal number 02-56491. The panel should proceed to decide that appeal.
. The rule provides in relevant part: "The district court may extend the time to file a notice of appeal if: (i) a party so moves no later than 30 days after the time prescribed by this Rule 4(a) expires; and (ii) ... that party shows excusable neglect or good cause.” Fed. R.App. P. 4(a)(5)(A).
. Although Evbuomwan is an unpublished opinion, Judge Garza noted that, under Fifth Circuit Rule 47.5.3, it was binding precedent. Midwest Employers Cas. Co., 161 F.3d at 882 n. 7.