One rep max
calculator.

Estimate your one rep max from a set you've already done — no need to test a true max — and see what to load for any rep range.

lb
reps

Use a hard set — one or two reps left in the tank at most. 1–15 reps.

Fill in the form to see your result.

Estimated one rep max
—
RepsWeight% of 1RM

Track it every day. Luntrack uses this exact method and adjusts as your weight and training change.

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How it's calculated

The method,
in plain words.

The Epley formula

1RM = weight × (1 + reps ÷ 30). It's the formula Luntrack uses to track your strength trend on every lift.

Most accurate at low reps

Estimates from sets of 2–6 reps are the most reliable. Above 10–12 reps, fatigue and technique make any formula less precise.

Working back to other rep ranges

The table runs the same formula in reverse: the heaviest weight you should manage for each number of reps.

For general fitness guidance only — not medical advice. If you're pregnant, have a medical condition or take medication that affects appetite or fluids, check with a doctor first.

FAQ

Good questions.

Is it safe to test a real 1RM?

It can be with good technique, a spotter and a proper warm-up — but for most people an estimate from a hard set of 3–5 is just as useful and much less risky.

Which rep count gives the best estimate?

A set taken close to failure with 2–6 reps.

How do I use %1RM in training?

Strength work usually sits around 80–90% of 1RM for 3–6 reps; muscle-building work around 65–80% for 6–12.

Does Luntrack track this automatically?

Yes. Every set you log updates an estimated 1RM per exercise, and your plan uses it to set the next session's weights.