How does Lift Frequency Calculator work?

It is based on same data as MEV & MRV calculator, factoring in your gender, weight, height, strength level, experience, age, diet, sleep, stress away form training, historical workload and historcial recovery ability. Remember that even if this tool is pretty accurate, the results should be used more as a reference point. It is kind of obvious that if you can menage only 3 lifting sessions in week you won't have a possibility to bench 4x a week.

Why does frequency even matter?

Frequency matters because you simply can't perform all of your volume for the lift in the same day. At least not in the Hypertrophy phase. Why? Because it would simply put your body under too much stress for you to be able to recover form it in time. Furthermore , more sessions mean more occasions to polish your technique which is crucial for lifting more.