1RM CALCULATOR

How the 1RM calculator works

Your one rep max (1RM) is the heaviest weight you can lift for a single clean rep. Testing it often is tiring and carries more risk, so most athletes estimate it from a hard set of 2 to 10 reps instead. Enter the weight and the reps you completed with good form, and the calculator does the rest.

The main number uses the Brzycki formula, the same one the FreeWOD app uses for its estimated 1RM: weight × 36 / (37 − reps). For comparison you also see the Epley formula: weight × (1 + reps / 30). Both are close for low reps and drift apart as reps go up.

The percentage chart is rounded to the nearest 2.5 kg or 5 lb so you can load it with standard plates. Tap “Plates” on any row to see exactly what goes on the bar.

How to use your 1RM percentages

Strength work: 80–90%

Heavy sets of 2 to 5 reps live here, for example 5×3 at 85% on squats or deadlifts. Leave a rep in the tank on most sets.

Volume and technique: 65–80%

Classic 5×5 or 4×8 work, plus complexes and barbell cycling in WODs. This is where most strength programs spend their time.

Speed and warm-ups: 50–65%

Fast, crisp reps for warm-ups, speed pulls or EMOM technique work. Use this range to build up to your working sets.

How accurate is an estimated 1RM?

Estimates are most reliable from sets of 10 reps or fewer, done close to failure with solid form. They differ between lifts and between people, so treat the number as a starting point and update it as you log new sets.

Track your PRs in FreeWOD

A calculator gives you one number. A log shows you the trend. FreeWOD is a free workout tracker for iPhone and Android: log lifting sets with weight, reps and RPE, and the app tracks your PRs and estimated 1RM per lift automatically, with the same Brzycki formula you see here. No account, no ads, and your data stays on your device.