[DO NOT PUBLISH]

IN THE UNITED STATES COURT OF APPEALS

 FOR THE ELEVENTH CIRCUIT

 ________________________

 No. 11-15932 

Non-Argument Calendar

 ________________________

 D.C. Docket No. 8:10-cr-00019-VMC-TBM-1

UNITED STATES OF AMERICA, 

llllllllllllllllllllllllllllllllllllllll Plaintiff-Appellee,

 versus

TRISTAN DAVIS, 

llllllllllllllllllllllllllllllllllllllll Defendant-Appellant.

________________________

 Appeal from the United States District Court

 for the Middle District of Florida

 ________________________

(October 26, 2012)

Before TJOFLAT, BARKETT and KRAVITCH, Circuit Judges.

PER CURIAM:

Case: 11-15932 Date Filed: 10/26/2012 Page: 1 of 3 
Tristan Davis appeals his 57-month sentence, imposed after pleading guilty

to conspiracy to possess with intent to distribute, and to distribute oxycodone, in

violation of 21 U.S.C. §§ 841(a)(1), (b)(1)(C), and 846 (“Count 1”); and attempt to

possess with intent to distribute oxycodone, in violation of 21 U.S.C. §§ 841(a)(1),

(b)(1)(C), and 846 (“Count 2”). Davis argues that the district court clearly erred in

holding him accountable for 4,600 oxycodone tablets, which was the quantity

estimated from post-arrest statements from Davis and his codefendant regarding

the weekly shipments that Davis received during the course of the conspiracy.

We review a district court’s factual determination of the drug quantity

attributable to a defendant for clear error. United States v. Rodriguez, 398 F.3d

1291, 1296 (11th Cir. 2005). We cannot find clear error unless we are left with “a

definite and firm conviction that a mistake has been committed.” United States v.

Crawford, 407 F.3d 1174, 1177 (11th Cir. 2005) (quotation omitted). When a

defendant objects to a factual finding used to calculate his guideline sentence,

such as drug amount, the government must establish the disputed fact by a

preponderance of reliable and specific evidence. Rodriguez, 398 F.3d at 1296; 

United States v. Lawrence, 47 F.3d 1559, 1566 (11th Cir. 1995). Sentencing

errors are harmless if they do not substantially affect the defendant’s sentence. 

United States v. Foley, 508 F.3d 627, 634 (11th Cir. 2007). 

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Case: 11-15932 Date Filed: 10/26/2012 Page: 2 of 3 
The Guidelines direct the court to approximate the quantity of the controlled

substance when there is no drug seizure or the amount seized does not reflect the

scale of the offense. U.S.S.G. § 2D1.1, comment. (n.12). We have held that,

“[a]lthough sentencing may be based on fair, accurate, and conservative estimates

of the quantity of drugs attributable to a defendant, sentencing cannot be based on

calculations of drug quantities that are merely speculative.” United States v.

Zapata, 139 F.3d 1355, 1359 (11th Cir. 1998). Undisputed statements found in

the PSI can be considered to be admissions of fact for sentencing purposes. 

United States v. Beckles, 565 F.3d 832, 844 (11th Cir. 2009).

The district court’s finding that Davis was accountable for about

4,600 oxycodone pills was supported by the record and not clearly erroneous. 

Alternatively, Davis was not harmed by any error the court made in determining

the drug quantity for which he was held responsible, given Davis’s concession that

the parcels could have contained a total of 4,300 oxycodone pills.

Upon review of the entire record on appeal, and after consideration of the

parties’ appellate briefs, we affirm. 

AFFIRMED. 

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Case: 11-15932 Date Filed: 10/26/2012 Page: 3 of 3