Glynn Farse Young appeals his convictions, following a jury trial, of conspiracy to possess with intent to distribute less than 50 kilograms of marijuana and possession of less than 50 kilograms of marijuana with intent to distribute, in violation of 21 U.S.C. §§ 841(a) and 846. The district court sentenced Young to concurrent 60-month prison terms and three-year terms of supervised release.

Young contends that the trial evidence was insufficient to support his conviction of either count. The standard for reviewing a claim of insufficient evidence is whether “a rational trier of fact could have found that the evidence establishes the essential elements of the offense beyond a reasonable doubt.” United States v. Villarreal, 324 F.3d 319, 322 (5th Cir. 2003) (citing Jackson v. Virginia, 443 U.S. 307, 319, 99 S.Ct. 2781, 61 L.Ed.2d 560 (1979)). Review of the sufficiency of the evidence does not include review of the weight of the evidence or of the credibility of the witnesses. United States v. Garcia, 995 F.2d 556, 561 (5th Cir. 1993).

Young’s primary contention is that his confessions made to both Border Patrol and Drug Enforcement Administration agents on the day of his arrest were not *444 sufficient, standing alone, to support his convictions. See United States v. Reynolds, 367 F.3d 294, 297 (5th Cir. 2004) (“a defendant generally cannot be convicted solely on his uncorroborated admissions”). As the Government argues, however, independent evidence of Young’s guilt was adduced at trial. See United States v. Crawford, 52 F.3d 1303, 1309 (5th Cir. 1995). Young was a passenger in a rental ear that had been rented and was driven by his codefendant, Allen William Woudstra. Although Young’s mere presence in the car as a passenger was not sufficient by itself to establish his knowing possession of the 48 kilograms of marijuana that were in the car’s trunk, it is a factor to be considered in weighing the circumstantial evidence. See United States v. Roberson, 6 F.3d 1088, 1093 (5th Cir. 1993). Young’s calm demeanor at the time of his and Woudstra’s arrest also indicted that Young was aware of the marijuana’s presence in the car. Finally, the jury was authorized to believe that the testimony given by Young at trial was implausible, at least in comparison to the stories he told Border Patrol and DEA agents. Young’s trial testimony required the jury to believe that Woudstra was paying Young $1,000 to ride with him hundreds of miles to Texas from their Tennessee hometown so that Young could help him drive back a “class [pickup] truck.” Both the basic outline of the story offered at trial and some its details were less than believable.

The evidence was sufficient to support the conspiracy conviction, because it established that there was an agreement to possess marijuana with intent to distribute, that Young knew about the agreement, and that he voluntarily participated in the conspiracy. See United States v. Peters, 283 F.3d 300, 307 (5th Cir.), cert. denied, 536 U.S. 934, 122 S.Ct. 2612, 153 L.Ed.2d 797 (2002). The evidence was also sufficient to support the possession conviction, in that it showed that the possession was knowing, see United States v. Mendoza, 226 F.3d 340, 345 (5th Cir. 2000), and in that the large quantity of marijuana reflected an intent to distribute. United States v. Redd, 355 F.3d 866, 873 (5th Cir. 2003).

Young’s convictions are AFFIRMED.