INTRODUCTION: To assess whether volumetric measurements can differentiate functional changes between reconstructive techniques after partial nephrectomy. MATERIALS AND METHODS: One hundred and fifty-six patients undergoing partial nephrectomy for a single renal mass were retrospectively studied between 2008 and 2012. Computed tomography scans were available for volume calculations on 56 (18 non-renorrhaphy and 38 renorrhaphy). Institutional review board approval was obtained. The primary outcome was %volume loss in the operated kidney, which was calculated from three-dimensional reconstructions using a semiautomatic segmentation algorithm. Multivariable regression and propensity score analysis was performed. RESULTS: Volumetric analysis detected a difference in mean %volume loss between two-layer reconstruction (cortical renorrhaphy and base-layer) and base-layer only (15.6% versus 3.8%, p < 0.001). The mean %glomerular filtration rate (GFR) loss was also greater in the two-layer group (8.9% versus 2.4%, p = 0.03). Demographics were similar between groups except the two-layer group was older, had more males, and increased ischemia time. On multivariable regression the presence of two-layer closure (β = -15.2%, p < 0.001) and tumor diameter (β = -7.4, p = 0.004) were significant predictors of %volume loss while ischemia time (p = 0.88) was not. Two-layer closure remained a predictor on propensity-adjusted analysis (β = -14.3, p = 0.004). The base-layer only group had two (5.3%) urine leaks and two (5.3%) bleeding complications. The two-layer group had two (1.7%) urine leaks and three (2.5%) bleeding complications (p = 0.23, 0.41). CONCLUSIONS: Volume loss calculated from CT scans can be used to monitor postoperative renal function. Techniques for renal reconstruction and tumor diameter are associated with volume and functional loss after partial nephrectomy and should be controlled for in future studies.