How to use this calculator
- Enter the weight you lifted and choose kg or lb.
- Enter how many clean repetitions you completed (1–15; 10 or fewer is most accurate).
- Use the table to choose weights for your programme, for example 5 reps at about 85% of 1RM.
Formula
Each formula models how reps decrease as load increases. The result shown is the average of five well-known equations.
Epley: 1RM = w × (1 + r / 30)
Brzycki: 1RM = w × 36 / (37 − r)
Lombardi: 1RM = w × r^0.10
Example
- 100 kg for 5 reps.
- Epley: 100 × (1 + 5/30) = 116.7 kg; Brzycki: 100 × 36 / 32 = 112.5 kg.
- Averaging the formulas gives about 115 kg.
Frequently asked questions
Is it safe to test a true 1RM?
Maximal lifts carry injury risk, especially for beginners. Estimating from a 3–8 rep set is safer and accurate enough for programming.
Why do the formulas give different results?
They were fitted to different groups of lifters and exercises. Differences grow with higher rep counts.
Does it work for every exercise?
It works best for compound barbell lifts like squat, bench press and deadlift. Machine and isolation exercises can differ.