Hi, I found a reproducible issue with the Takeoff Performance calculator. Using the exact same aircraft, airport, runway and weather, simply changing the OIS weight unit from Tonnes to x1000 lbs results in different takeoff performance calculations. The aircraft weight is identical: 273.1 t = 602.1 x1000 lbs However, the calculated V-speeds are different: Tonnes V1 149 VR 152 V2 161 TOGA x1000 lbs V1 137 VR 140 V2 146 FLEX 67°C Changing the weight unit should only affect the display, not the performance calculation. I've attached screenshots showing both results.