One Rep Max (1RM) Calculator

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Estimate your one-rep max from a lighter set using the Epley, Brzycki or Lombardi formula, plus a full training-percentage table for every lift.

kg
Estimated 1RM –
Training percentages
% Weight Reps
Estimates are most accurate for sets under 10 reps. Train within your limits and use a spotter for maximal lifts.

About One Rep Max (1RM) Calculator

The one rep max calculator estimates the heaviest weight you could lift for a single repetition — your 1RM — from a lighter set taken to a known rep count. Enter the weight lifted and the reps completed, and choose between three established formulas: Epley, Brzycki and Lombardi.

Each formula converts submaximal work differently: Epley computes weight × (1 + reps ÷ 30), Brzycki uses weight × 36 ÷ (37 − reps), and Lombardi applies weight × reps^0.10. Estimates are most reliable for sets under 10 reps. Alongside the 1RM you get a full training-percentage table showing the load and typical rep count for each intensity.

Whether you need a one rep max calculator for bench press, squat or deadlift, this saves you from testing a true max — a demanding and riskier lift. Free, instant and browser-based, in kg or lb.

How to use One Rep Max (1RM) Calculator

  1. Select metric or imperial units.
  2. Enter the weight you lifted and how many reps you completed.
  3. Pick a formula: Epley, Brzycki or Lombardi.
  4. Read your estimated 1RM and the training-percentage table for programming your sets.

Frequently asked questions

Epley and Brzycki agree closely for moderate reps and are the most widely used; Lombardi tends to run higher at high rep counts. Compare all three here — the spread shows the estimate’s uncertainty.

Best within about 10 reps of a true max: a heavy set of 3–5 reps predicts well, while sets of 12+ drift because endurance starts to dominate. Individual leverages and training style add variance.

Programming. Strength work is often prescribed as a percentage of 1RM — for example, 5 reps at 85%. The table converts your estimated max into the actual weight for each percentage.

Usually not. Estimating from a hard submaximal set gives most of the information with far less strain and risk. If you do attempt a true max, warm up thoroughly and use a spotter.

No — the numbers are general estimates for planning. Train within your limits, progress gradually, and consult a qualified coach or physician if you are new to heavy lifting.
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