About the Estimated Reps Calculator
How many reps you should manage at a given weight, based on your one rep max.
Also known as: reps at weight, rep max predictor, how many reps can i do.
How to use this calculator
- Enter one rep max, working weight.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
Brzycki rearranged: reps = 37 − 36 ÷ (weight ÷ 1RM)
Worked example
Using the values pre-filled in the calculator above:
- One rep max = 140
- Working weight = 110
the calculator returns:
- Estimated reps: 1
- Percentage of 1RM: 78.6%
- Epley estimate: 8 reps