Objective: Measurements of body volume (Vb), body density (Db), predicted thoracic gas volume (Vtgpred),and percent fat (%Fat) using the self-testing air displacement plethysmography unit (Bod Pod S/T) were compared to measurements determined using the original air displacement plethysmography unit (Bod Pod). In addition, %Fat measurements from the Bod Pod S/T were compared to %Fat measures from hydrostatic weighing (HW) and total body dual energy X-ray absorptiometry scans (DXA). Methods: Standing height, followed by Bod Pod S/T, Bod Pod, HW with measured residual lung volume, and DXA scans were completed by 42 young adults. Measurements of Vb, Db, Vtgpred, thoracic gas volume (Vtgmeas) and %Fat were subsequently determined and compared. Results: Significant mean differences (mean ± SE) of Vb = 0.159 ± 0.045 litres (l), Db = -0.0049 ± 0.0008 g/cc, Vtg = -0.235 ± 0.096 l and 2.2 ± 0.3 %Fat were found between the Bod Pod S/T and the Bod Pod (P<0.05). Significant mean differences in %Fat measures were found between the Bod Pod S/T and HW (1.8 ± 1.5%), but there were no significant differences between Bod Pod S/T and DXA (0.6 ± 1.5%). Significantly strong correlation coefficients were found for all body composition measures between the Bod Pod S/T and Bod Pod, HW and DXA. Conclusions: The Bod Pod S/T produced small systematic differences of little physiological and methodological consequences, resulting in only a minor impact to the resulting body composition measurements. Hence, the Bod Pod S/T is a viable alternative to traditional body composition measuring techniques.