The most accurate way to calculate 1RM (one repetition maximum) is with a load velocity profile using a velocity based training app like Metric VBT. Velocity Based Training (VBT) is used to calculate 1RM from a series of sub-maximal sets using velocity and load data. This method allows for real-time 1RM estimation from submaximal sets and accounts for daily fluctuations in physical performance and strength levels​``【oaicite:16】``​.