One Rep Max Calculator
Enter a positive weight and reps between 1-15 (estimates get unreliable above that).
Training percentages (based on Epley average)
| %1RM | Weight |
|---|
Both formulas are estimates from a single set — they get less reliable above about 10 reps, and the two formulas diverge more as rep count increases. For a true 1RM, an actual max-effort attempt (with a spotter) is the only precise measurement.
Free one rep max calculator showing both the Epley and Brzycki formulas side by side, plus a full training percentage table (60-95% of 1RM) — not just a single estimated max.
How it works
- Enter the weight you lifted and how many reps you completed
- See your estimated 1RM from both Epley and Brzycki formulas
- See a training percentage table for programming your next sets
Frequently asked questions
Why do Epley and Brzycki give different numbers?
They're both estimates built from different underlying rep-max data, and they diverge more as rep count increases — showing both instead of just one makes that uncertainty visible rather than presenting a single falsely-precise number.
How accurate is this compared to an actual max attempt?
These formulas estimate from a single submaximal set and get less reliable above about 10 reps. An actual max-effort attempt with a spotter is the only precise measurement — treat this as a training-planning estimate.
Related tools
From the blog
Update history
- 2026-09-03 Bounded numeric fields are now sliders instead of number inputs.
- 2026-09-01 Added: a cover image — used as the card thumbnail, social share image, and blog title image.
- 2026-09-01 Launched: one rep max calculator with both Epley and Brzycki formulas plus a training percentage table. Entirely client-side.