GFRP bars are widely used as embedded reinforcement due to their inherent corrosion resistance. Bending these bars is only possible during manufacturing due to their thermoset resin matrix, on-site bending is not feasible. Due to fiber kinking and transverse stresses, bent GFRP bars have lower tensile strength than their straight segments, therefore special test setups emerged, to test the bent strength of GFRP bars. Although the bent strength measurements from different setups may be similar, the relative displacement values between the GFRP and the concrete surfaces can vary significantly. This study compares three bent strength test setups recommended by three different organizations: ACI, CSA, and JSCE, using nonlinear finite element modeling. The validation of the numerical model was done based on available laboratory test results from literature. A 12 mm diameter GFRP bar was investigated with a bent diameter seven times the nominal diameter. Tail lengths of five, ten, and twelve times the nominal diameter were tested, as well as two different concrete strengths, C30/37 and C50/60. In combination with the test setups, 18 different cases were tested numerically. The results showed that the different test setups provide different levels of confinement for the tested bent GFRP bar, causing significant differences in the measured slippage and minor differences in the measured bent strength. Therefore, if no splitting failure occurs, all test setups are suitable to measure bent strength, however, consensus is needed for which test setup to use to determine the adequate tail length for bent GFRP bars.