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One Rep Max Calculator

Estimate your one rep max from a lighter set, and get a training table from 50% to 95%.

Results

FormulaEstimated 1RM

Training loads

% of 1RMLoad
This is an estimate. Accuracy varies by exercise and experience, and it falls at higher reps. Do not test a true maximum without a spotter and proper technique. Speak to a doctor if you are new to strength training or have an injury.

Quick Answer

Your one rep max (1RM) is the most you could lift for one rep. The Epley formula estimates it as weight × (1 + reps ÷ 30), and Brzycki as weight × 36 ÷ (37 − reps). If you lift 225 lb for 5 reps, Epley gives 262.5 lb, Brzycki gives 253.1 lb, and the average is 257.8 lb.

Last updated: 2 November 2026 · How we calculate this: Epley and Brzycki formulas

Table of Contents

How This One Rep Max Calculator Works

A one rep max is the heaviest weight you can lift once with good form. Testing it directly can be risky, so this calculator estimates it from a lighter set. It shows two widely used formulas side by side, along with their average.

Quick explanation: enter the weight and the reps you completed. The fewer reps, the more reliable the estimate.

  • Weight: the load you lifted.
  • Reps: completed with good form, from 1 to 12.
  • Training table: loads from 50% to 95% of your estimate.

Core Formulas

  • Epley: 1RM = weight × (1 + reps ÷ 30)
  • Brzycki: 1RM = weight × 36 ÷ (37 − reps)
  • Average: (Epley + Brzycki) ÷ 2

The two formulas match at 10 reps. Below that, Epley gives a higher number. For a single rep, this calculator uses the weight lifted as the Epley result.

Worked Example

You lift 100 kg for 10 reps.

  • Epley = 100 × (1 + 10 ÷ 30) = 133.3 kg
  • Brzycki = 100 × 36 ÷ 27 = 133.3 kg
  • 80% training load = about 106.7 kg

Why Your Result May Differ

  • Exercise: studies found accuracy changes between lifts.
  • Experience: estimates can be less accurate for beginners.
  • Reps: sets of about 2 to 6 reps usually give a closer estimate than long sets.
  • Fatigue: use a set done when you are fresh, with good form.

Frequently Asked Questions

Lift a weight for several good reps, then enter the weight and reps here. A common formula is weight × (1 + reps ÷ 30).

No formula is best for everyone. Accuracy depends on the lift and the lifter, so this calculator shows two formulas and their average.

It depends on your goal and experience. Use the training table as a guide, and follow a program suited to you.

Beginners are usually safer estimating it from a lighter set. Get advice from a qualified coach before lifting near your maximum.

Estimates become less reliable as reps increase, so this calculator stops at 12.

References & Sources

SourceUsed ForLink
Validity of predictive equations for 1RM (University of the Sunshine Coast record) How accuracy changes by exercise. https://research.usc.edu.au/esploro/outputs/journalArticle/Validade-das-equações-preditivas-de-uma/99448976802621
Wikipedia, One-repetition maximum Epley and Brzycki formulas. https://en.wikipedia.org/wiki/One-repetition_maximum