                  FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 05-30112
                 Plaintiff-Appellee,
               v.                            D.C. No.
                                           CR-04-0144-EJL
JOSHUA R. KILBY,
                                             OPINION
             Defendant-Appellant.
                                       
        Appeal from the United States District Court
                  for the District of Idaho
         Edward J. Lodge, District Judge, Presiding

                  Argued and Submitted
             March 8, 2006—Portland, Oregon

                     Filed April 7, 2006

 Before: Ferdinand F. Fernandez, A. Wallace Tashima, and
             Richard A. Paez, Circuit Judges.

                 Opinion by Judge Tashima




                            3871
3874                UNITED STATES v. KILBY


                         COUNSEL

James K. Ball, Manweiler, Manweiler, Breen & Ball, PLLC,
Boise, Idaho, for the defendant-appellant.

Alan G. Burrow, Assistant United States Attorney, Boise,
Idaho, for the plaintiff-appellee.


                          OPINION

TASHIMA, Circuit Judge:

  Defendant Joshua R. Kilby (“Kilby”) was convicted of con-
spiracy to distribute and possess with intent to distribute con-
                    UNITED STATES v. KILBY                  3875
trolled substances in violation of 21 U.S.C. §§ 841 and 846.
On appeal, Kilby argues that the evidence was insufficient to
sustain his conviction. Kilby also appeals his sentence on
three grounds, arguing that the district court erred in: (1) cal-
culating the amount of 5-MEO-DIPT (“Foxy”) attributable to
Kilby; (2) deciding the amount of MDMA (“Ecstasy”) attrib-
utable to Kilby; and (3) imposing an unreasonable sentence.
We have jurisdiction pursuant to 18 U.S.C. § 3742 and 28
U.S.C. § 1291. We affirm Kilby’s conviction, but vacate his
sentence and remand for resentencing.

                      BACKGROUND

   Prior to 2002, Kilby and Eric Lucker (“Lucker”) worked
together to sell Ecstasy. In 2002, Kilby was convicted of drug
trafficking in Washington, and was sentenced to two years in
prison, which he began serving in October 2002. Kilby and
Lucker started to work together again in the summer of 2002,
before Kilby started his prison term. Kilby introduced Lucker
to several other people, as part of a plan to manufacture and
sell Ecstasy and Foxy. When Kilby went to prison, Lucker
agreed to sell drugs for Kilby and send him payments while
he was in jail. Lucker did in fact make several payments to
Kilby during 2003, which totaled over $1000.

   While in prison, Kilby became friends with John Anthony
(“Anthony”), another convicted drug trafficker. Shortly before
Anthony’s release in May 2003, Kilby propositioned Anthony
about resuming his drug trade in concert with Kilby’s asso-
ciates. Specifically, Kilby told Anthony to contact Lucker,
who would sell Ecstasy to Anthony to get him started again
in the business. Anthony played along with Kilby, but had no
intention of going back into the drug trade.

  After being released from prison, Anthony contacted Drug
Enforcement Administration (“DEA”) Agent Niles Gooding
and informed him about his conversations with Kilby. On
Agent Gooding’s instructions, Anthony phoned Lucker and
3876                UNITED STATES v. KILBY
inquired about buying Ecstasy. Lucker only agreed to sell
Ecstasy to Anthony after obtaining confirmation from Kilby
about him. Pursuant to Agent Gooding’s instructions,
Anthony told Lucker that he could not travel to Seattle to pur-
chase the drugs, and offered to send his “friend” instead.
Anthony’s “friend” was Agent Gooding.

   Over the course of several months, Agent Gooding made
three purchases from Lucker totaling 2500 pills of Ecstasy.
During those purchases, Lucker discussed sending money to
Kilby as part of the overall deal. Records show that Lucker
sent Kilby money within days of Agent Gooding’s first two
purchases. After setting up one more purchase with Lucker,
Agent Gooding arrested him in March 2004.

                PROCEDURAL HISTORY

   Kilby was indicted for conspiracy to distribute and posses-
sion with intent to distribute Ecstasy and Foxy in violation of
21 U.S.C. §§ 841 and 846. During the three-day jury trial,
after the government rested, Kilby made a motion for acquit-
tal. Kilby argued that the alleged conspiracy had not been
proved because Lucker had withdrawn from the conspiracy.
The district court denied the motion, stating that the question
of withdrawal was a fact to be found by the jury. The jury
found Kilby guilty of the conspiracy and determined that he
had conspired to distribute/possess with intent to distribute
2500 tablets of Ecstasy and 7000 tablets of Foxy. No Foxy
tablets were seized in the case, however, so it was not possi-
ble to measure the weight of those tablets.

  In the first Presentence Investigation Report (“PSR”), the
probation officer estimated the weight of the Foxy tablets by
considering the DEA’s recommended dosage of the drug and
Foxy’s heightened potency as compared to another known
drug, DMT. This calculation, when combined with the
amount of Ecstasy, resulted in a base offense level of 24
under the Sentencing Guidelines.
                    UNITED STATES v. KILBY                  3877
   Kilby objected to the first PSR, arguing that it was legally
improper to consider the potency of Foxy in determining the
weight of the tablets. The probation officer agreed and issued
a second PSR. In the second PSR, the probation officer esti-
mated the weight of the Foxy tablets by considering two cases
in which actual Foxy tablets had been recovered. In one case,
from Virginia, the tablets each weighed 140 milligrams, and
in the second case, from California, the tablets each weighed
235 milligrams. Considering these weights together, the offi-
cer conservatively estimated the weight of the tablets in this
case to be 100 milligrams each. This calculation resulted in a
base offense level of 26.

   Kilby objected to the second PSR, arguing that there was
an insufficient factual basis for the finding of the weight of
the Foxy tablets. The district court nonetheless adopted the
calculations in the second PSR, finding that 100 milligrams
per Foxy tablet was a conservative estimate that gave the ben-
efit of the doubt to Kilby. The court, however, did not want
to punish Kilby for identifying the error in the first PSR. The
court also wanted to be very conservative in its estimate of the
amount of Foxy. Therefore, the court used a base offense
level of 24, as recommended by the first PSR.

   Factoring in adjustments for Kilby’s role in the offense and
for his criminal history, the court found the applicable Guide-
lines range to be 92 to 115 months. In imposing the sentence,
the district court considered the Guidelines, the policies of the
Sentencing Commission, and the factors listed in 18 U.S.C.
§ 3553(a). The court acknowledged that the Guidelines were
advisory, but concluded that the Guidelines range was “appro-
priate and should be applied in this case.” The court thus
imposed a sentence of 96 months’ imprisonment, followed by
five years of supervised release. Kilby timely appeals.
3878                UNITED STATES v. KILBY
                         ANALYSIS

I.   Sufficiency of the Evidence

   [1] Kilby contends that there was insufficient evidence to
prove the charged conspiracy because Lucker had withdrawn
from the conspiracy prior to selling Ecstasy to Agent Good-
ing. “Where a defendant moves for acquittal at the close of
the government’s evidence, we review de novo whether suffi-
cient evidence exists to support a guilty verdict.” United
States v. Stewart, 420 F.3d 1007, 1014 (9th Cir. 2005). “Evi-
dence is sufficient if, viewed in a light most favorable to the
prosecution, any rational trier of fact could have found the
essential elements of the crime beyond a reasonable doubt.”
United States v. Odom, 329 F.3d 1032, 1034 (9th Cir. 2003).

   [2] “A conspirator can withdraw from a conspiracy by: (1)
disavowing the unlawful goal of the conspiracy; (2) affirma-
tively acting to defeat the purpose of the conspiracy; or (3)
taking definite, decisive, and positive steps to disassociate
himself from the conspiracy.” United States v. Fox, 189 F.3d
1115, 1118 (9th Cir. 1999) (internal quotation marks omitted).
Kilby bases his argument on Lucker’s testimony that he told
Kilby in mid-2003 that he was “fed up with the drug busi-
ness” and that he was “done dealing drugs.” A review of the
record, however, demonstrates that the jury had ample evi-
dence on which to base a finding that Lucker did not in fact
withdraw from the conspiracy.

   [3] First, Lucker’s own testimony is equivocal. Immedi-
ately after he made the statements cited by Kilby, Lucker also
testified on cross-examination that he never withdrew from
the conspiracy:

     Q:   And the deal was done, is that correct, because
          Josh [Kilby] couldn’t sell drugs?

     A:   The deal never ended. I didn’t talk to Josh about
          ending the deal.
                     UNITED STATES v. KILBY                  3879
In addition, Lucker also testified on cross that he talked about
“getting out of the drug business” before Anthony contacted
him. Lucker therefore confirmed Anthony’s request to pur-
chase Ecstasy with Kilby after his comments about quitting
the drug business. Finally, on redirect examination, Lucker
asserted that he had not testified that he told Kilby he “quit
the drug business,” and did not recall having a conversation
where he told Kilby that he quit. Thus, Lucker himself con-
firmed that he did not withdraw from the conspiracy, but
rather continued his participation in it.

   [4] Second, evidence of Lucker’s conduct supports the
finding that he never withdrew from the conspiracy. Lucker
sent Kilby money both prior to and after his alleged with-
drawal. Lucker agreed to sell Ecstasy to Anthony after getting
confirmation from Kilby. And Lucker, while selling Ecstasy
to Agent Gooding, discussed sending some of the proceeds to
Kilby. This evidence, when combined with Lucker’s self-
contradictory testimony, and considered in the light most
favorable to the government, is sufficient to support the find-
ing that Lucker did not withdraw from the conspiracy. See
Stewart, 420 F.3d at 1015 (“We must respect the province of
the jury to ascertain the credibility of witnesses, resolve evi-
dentiary conflicts, and draw reasonable inferences from
proven facts, by assuming that the jury resolved all such mat-
ters in a manner which supports the verdict.” (internal quota-
tion marks omitted)). Accordingly, we affirm Kilby’s
conviction.

II.    Review of Kilby’s Sentence

  A.    Standard and Method of Review

   When we review a sentence, the first step is to determine
if the district court made a material error in its Guidelines cal-
culation that serves as the starting point for its sentencing
decision. United States v. Cantrell, 433 F.3d 1269, 1280 (9th
Cir. 2006). If there was material error in the Guidelines calcu-
3880                   UNITED STATES v. KILBY
lation, we will remand for resentencing, without reaching the
question of whether the sentence as a whole is reasonable. Id.
If the district court committed no error in applying the Guide-
lines, we will next consider challenges to the reasonableness
of the overall sentence in light of the factors specified in 18
U.S.C. § 3553(a). Id.

   With regard to the Guidelines calculation, we review de
novo whether the district court applied the correct burden of
proof in attributing drug quantity to a defendant. United States
v. Banuelos, 322 F.3d 700, 704 (9th Cir. 2003). We review a
district court’s interpretation of the Guidelines de novo. Can-
trell, 433 F.3d at 1279. We also review de novo whether a dis-
trict court’s method of approximation of the relevant drug
quantity conforms to the Guidelines. United States v.
Rosacker, 314 F.3d 422, 425 (9th Cir. 2002). The district
court’s factual findings are reviewed for clear error. Cantrell,
433 F.3d at 1279.

  B.    Determination of Amount of Foxy

   [5] Kilby contends that the district court erred in estimating
the amount of Foxy attributable to him in its Guidelines calcu-
lation because the method of estimation was unreasonable and
did not amount to proof beyond a reasonable doubt. As an ini-
tial matter, Kilby’s contention that the drug quantity finding
must have been proved beyond a reasonable doubt is mis-
taken. We have held that following United States v. Booker,
543 U.S. 220 (2005), district courts should resolve factual dis-
putes at sentencing by applying the preponderance of the evi-
dence standard. See United States v. Ameline, 409 F.3d 1073,
1086 (9th Cir. 2005) (en banc) (citing United States v. How-
ard, 894 F.2d 1085 (9th Cir. 1990)); see also United States v.
Dare, 425 F.3d 634, 642 (9th Cir. 2005) (“As a general rule,
the preponderance of the evidence standard is the appropriate
standard for factual findings used for sentencing.”).1 There-
  1
   In some cases, where a sentencing factor would have an extremely dis-
proportionate effect on the sentence, the government may have to satisfy
                       UNITED STATES v. KILBY                        3881
fore, the district court did not err by failing to require that the
quantity of Foxy be proved beyond a reasonable doubt.

   Kilby argues that, even if the correct standard is preponder-
ance of the evidence, the district court’s finding did not meet
that standard. Specifically, Kilby contends that the district
court’s method of approximating the weight of the Foxy tab-
lets was not sufficiently reliable.

   [6] The applicable Guidelines range for a drug trafficking
crime depends upon the weight of drugs involved. United
States v. Culps, 300 F.3d 1069, 1076 (9th Cir. 2002);
U.S.S.G. § 2D1.1(a), (c) (2004). With tablets or pills, the
entire weight of the tablet is used in the Guidelines calcula-
tion, not just the weight of the pure controlled substance.
United States v. Crowell, 9 F.3d 1452, 1454 (9th Cir. 1993).
Where none of the drugs has been seized, the district court
may approximate the weight of the drugs. See United States
v. August, 86 F.3d 151, 154 (9th Cir. 1996); U.S.S.G.
§ 2D1.1, cmt. n.12.2

   “Approximations of drug quantity must meet three
criteria.” Culps, 300 F.3d at 1076. First, “the government is
required to prove the approximate quantity by a preponder-
ance of the evidence . . . [which means that] [t]he district

a clear and convincing standard of proof. See Dare, 425 F.3d at 642. We
have previously held, however, that this exception does not apply to drug
quantity approximations, and that the correct standard is preponderance of
the evidence. See Rosacker, 314 F.3d at 430.
   2
     The comment provides:
    In making this determination, the court may consider, for exam-
    ple, the price generally obtained for the controlled substance,
    financial or other records, similar transactions in controlled sub-
    stances by the defendant, and the size or capability of any labora-
    tory involved.
U.S.S.G. § 2D1.1, cmt. n.12.
3882                    UNITED STATES v. KILBY
court must conclude that the defendant is more likely than not
actually responsible for a quantity greater than or equal to the
quantity for which the defendant is being held responsible.”
Id. (internal quotation marks and citation omitted). Second,
“the information which supports an approximation must pos-
sess sufficient indicia of reliability to support its probable
accuracy.” Id. (internal quotation marks omitted). Third, since
the “sentence depends in large part upon the amount of drugs
. . . and approximation is by definition imprecise, the district
court must err on the side of caution” in approximating the
drug quantity. Id.3

   [7] We have not previously evaluated an approximation
based upon the weights of drugs seized in completely unre-
lated cases. We have approved several different methods for
making drug quantity approximations, but in these methods,
the variables involved were all based on facts specific to the
defendant’s case. See, e.g., United States v. Alvarez, 358 F.3d
1194, 1213 (9th Cir. 2004) (approving approximation based
on co-conspirator testimony); Culps, 300 F.3d at 1077
(approving approximation based on multiplying an estimated
daily or weekly quantity by an applicable period of time);
August, 86 F.3d at 154-55 (approving approximation based on
lab capacity); United States v. Basinger, 60 F.3d 1400, 1409-
10 (9th Cir. 1995) (approving approximation based on two
empty, one-pound containers of ephedrine); see also United
States v. Gonzalez-Sanchez, 953 F.2d 1184, 1187 (9th Cir.
1992) (citing cases that approve of the method of converting
  3
    Kilby also claims that the district court had to make a reliable estimate
based upon case-specific information. This assertion is based on Applica-
tion Note 11 in § 2D1.1, which states that the Typical Weight Per Unit
Table can be used if the number of pills is known, but not the weight of
the controlled substance. The table should not be used “if any more reli-
able estimate of the total weight is available from case-specific informa-
tion.” U.S.S.G. § 2D1.1, cmt. n.11. The district court did not use, and
could not have used, the table, however, because Foxy is not one of the
substances listed in it. See id. Therefore, Application Note 11 does not
invalidate the district court’s method of approximation per se.
                        UNITED STATES v. KILBY                         3883
cash proceeds into equivalent amount of drugs); U.S.S.G.
§ 2D1.1, cmt. n.12 (stating that, when approximating quantity,
a court may consider “similar transactions in controlled sub-
stances by the defendant” (emphasis added)).

   [8] In contrast, the district court in this case based its
approximation on the weights of Foxy tablets seized in two
unrelated cases from different parts of the country. Based on
these circumstances, there is no reliable way to know whether
the Foxy tablets in this case had a similar weight to the tablets
in the other cases. The government presented no evidence that
Kilby’s case was in any way related to these other Foxy cases,
such as evidence of a common supplier. Nor did it present any
evidence that Foxy tablets are always the same approximate
size. To the contrary, the statistical “sample” only had two
pieces of data, and the weights in those cases were quite dif-
ferent. Cf. United States v. Scheele, 231 F.3d 492, 500 (9th
Cir. 2000) (“[T]he district court’s failure to consider the mar-
gin of error when arriving at the quantity of drugs on which
the sentence was based constitutes error. . . .”). Therefore, we
conclude that the district court’s method of approximation did
not possess sufficient indicia of reliability to serve as a basis
for calculating the quantity of Foxy. See Culps, 300 F.3d at
1076.4 Accordingly, we hold that the district court clearly
erred in its finding of the amount of Foxy involved.
  4
    On remand, the district court could rely on Lucker’s testimony that
there were three ounces of Foxy to approximate the weight of the Foxy
tablets, and that one ounce equals approximately 2500 pills, which calcu-
lates out to 10 milligrams per pill. While this testimony may produce a
significant underestimate, see Crowell, 9 F.3d at 1454, it is a more reliable
method of approximation and has some support in the Guidelines. See
U.S.S.G. § 2D1.1, cmt. n.11 (stating that some entries in the Typical
Weight Table list the weight of the actual controlled substance, as opposed
to the weight of the pill or capsule, and therefore produce very conserva-
tive weight estimates).
3884                UNITED STATES v. KILBY
  C.   Determination of Amount of Ecstasy

   Kilby contends that the district court erred in attributing
2000 Ecstasy pills to him for sentencing purposes. Specifi-
cally, he argues that such a quantity was not within the scope
of any agreement between him and Lucker, and that Lucker’s
sales were not reasonably foreseeable to Kilby.

   [9] “[I]n determining for purposes of sentencing the quan-
tity of drugs for which a conspirator will be held responsible,
the district court is required to determine the quantity of drugs
the conspirator reasonably foresaw or which fell within the
scope of his particular agreement with the conspirators.” Ban-
uelos, 322 F.3d at 702 (internal quotation marks omitted). The
record amply demonstrates that Lucker’s sales of Ecstasy
were reasonably foreseeable to Kilby. Kilby specifically
counseled and induced Anthony to buy “two boats” (2000
pills) of Ecstasy from Lucker. In addition, Lucker only agreed
to sell Ecstasy to Anthony after obtaining confirmation from
Kilby. Therefore, Lucker’s Ecstasy sales were specifically
contemplated by Kilby. Accordingly, the district court did not
err in attributing the 2000 Ecstasy pills to Kilby for sentenc-
ing purposes.

                       CONCLUSION

   The district court clearly erred in its Guidelines calculation
by using an insufficiently reliable method of approximating
the amount of Foxy attributable to Kilby. The district court’s
error was not harmless because, had it found the tablets to
each weigh 10 milligrams instead of 100 milligrams, Kilby’s
base offense level would have been 20 instead of 24, the level
assigned by the district court. See U.S.S.G. § 2D1.1(c). We
therefore vacate the sentence and remand for resentencing
without reaching the question of whether the sentence as a
whole was reasonable. See Cantrell, 433 F.3d at 1280.

 Conviction AFFIRMED; sentence               VACATED         and
REMANDED for resentencing.
