Automated peritoneal dialysis (APD) cycler systems and methods are disclosed. The APD cycler can include a heater tray with load cells configured to measure the weight of fluid contained within a heater bag and/or a drain bag. The load cells can be toggleable between enabled and disabled configurations. The APD cycler can include a pressure-based volume measurement system, which can be used to confirm measurements made by the load cells. In some embodiments, the APD cycler can have algorithms for tracking an estimated patient volume to prevent overfilling the patient.