How this calculator works
Brzycki estimated 1RM = lifted weight / (1.0278 − 0.0278 × completed repetitions). At one repetition the denominator is 1, so the estimate equals the lifted weight.
Use the total external load for one completed set performed near the repetition limit with consistent range of motion and technique. The percentage table multiplies the estimate by each percentage; it does not round to available equipment. The plate handoff transfers the unrounded selected load.
Reading your result
Exercise, experience, fatigue and how close the set was to failure influence accuracy. A comfortable set with repetitions in reserve may understate your capability. Estimates are not guarantees or instructions to attempt a maximum.
Illustrative worked example
80 kg for 5 repetitions gives 80 / 0.8888 = 90.01 kg estimated 1RM. 75% is approximately 67.51 kg before finding an achievable plate combination.
Supported inputs & limitations
For adults doing recreational resistance training. Whole repetitions from 1–10 and external loads 1–600 kg. This equation is not offered for high-repetition endurance sets, assisted movements, or bodyweight exercises with unclear effective load. Equipment and appropriate supervision matter.
Sources & methodology
These primary sources support the method and context. They do not endorse helsy or verify this implementation.