How to estimate 1RM
Use a set taken close to failure.
1
Warm up
Build to a challenging set with good form.
2
Enter weight and reps
Use a set of 1–8 reps for the best estimate.
3
Program percentages
Use 70–90% for most strength work.
What does this tool do?
A one-rep max is the heaviest weight you can lift once. This calculator uses the Epley formula to estimate it from a set taken close to failure, then shows common training percentages.
The Formula
1RM ≈ Weight × (1 + Reps ÷ 30)Frequently Asked Questions
Which 1RM formula is best?
Epley, Brzycki and Lombardi give similar estimates at low reps. The difference grows at higher rep counts; use the same formula for tracking.
Can I test a true 1RM?
Yes, with a proper warm-up, safety racks and a spotter. If you are new to lifting, use a rep estimate instead.