Background: To compare the characteristics of biometric measurements among the LS900, IOL Master, and OPD-SCAN III in patients with mild-to-moderate cataract. Methods: We recruited 85 eyes of 78 patients diagnosed with mild-to-moderate cataract at our hospital between January and April 2023. The K (average corneal curvature; K1 and K2), astigmatism (AST), and white to white (WTW) were measured using those three devices, respectively. Differences and correlations between those measures based on the device were explored. Results: The K1, K2, and AST were highly consistent among the groups (P = 0.851, P = 0.626, P = 0.473, respectively). The WTW measured by IOL Master were larger than those measured by the LS900 and OPD-SCAN III (all P < 0.001). However, all three devices were highly correlated in all measures (P < 0.001). Bland-Altman plots indicated a significant agreement between three devices in all measurements (P < 0.001). Conclusions: K1, K2, and AST in patients with mild-to-moderate cataract were similar among all three devices, whereas the WTW were not. WTW measurement differences between three devices should be concerned in cataract cases.