<i>Background:</i> We measured donor kidney weight (D-KW), functional renal volume (D-FRV), and single-kidney glomerular filtration rate (D-SKGFR), and then evaluated the impact of the indices to recipient body weight (R-BW) on graft function. <i>Methods:</i> This study included 44 recipients of live donor transplants without delayed graft function or acute rejection within 2 years of transplantation. <i>Results:</i> There was a statistically significant difference in serum creatinine between recipients with a D-KW/R-BW ratio of ≤4.25, D-FRV/R-BW ratio of ≤5.14, or D-SKGFR/R-BW ratio of ≤1.06 and recipients with a D-KW/R-BW ratio of >4.25, D-FRV/R-BW ratio of >5.14, or D-SKGFR/R-BW ratio of >1.06, respectively. D-KW/R-BW, D-FRV/R-BW, and D-SKGFR/R-BW strongly correlated with serum creatinine at 1 year and 2 years post-transplantation. In multivariate analysis, D-FRV and donor age were statistically significant risk factors which influenced serum creatinine at 1 year and 2 years post-transplantation. <i>Conclusion:</i> D-FRV/R-BW and donor age have significant impact on graft function. D-FRV/R-BW can be measured ahead of surgery. Therefore, measuring the D-FRV is useful to select a more optimal donor kidney among otherwise similar candidates during preoperative evaluation to improve posttransplant graft function.