One-rep max
calculator.

Enter a set you did: the weight, the reps, and how many reps you had left. The calculator estimates your one-rep max with Epley’s formula, counting the reps you had in reserve, and suggests starting loads for other rep targets. No maximum test needed.

ESTIMATED ONE-REP MAX

123.5 kg

From 100 kg × 5 with 2 reps left, using Epley’s formula on the 7 reps the set had in it. Treat it as an estimate, not a test result.

Starting loads for working sets from this estimate
Set	2 reps left	3 reps left
3 reps	105.5 kg	103 kg
5 reps	100 kg	97.5 kg
8 reps	92.5 kg	90 kg
10 reps	88 kg	86 kg
12 reps	84 kg	82 kg

Loads are rounded to 0.5 kg. Round down to the weights you have, and adjust after the first set if the reps left are not what you expected.

How the estimate works

Epley’s formula multiplies the weight by 1 + reps ÷ 30. This calculator, like the TrainHere app, counts the reps you had left as part of the set, up to 4: 100 kg for 5 reps with 2 left counts as 7 reps, an estimated 123 kg. It shows no estimate beyond 12 reps in total, because the formula drifts at high reps.

How accurate is it?

Prediction equations track tested maxima closely in groups, but differ by exercise and by person [LeSuer 1997]. Your reps-left estimate adds uncertainty too: people tend to underestimate it by about one rep [Halperin 2022]. Use the number to choose starting loads and to compare yourself with yourself, not as a target to test.

Do you need a one-rep max to train?

No. Rep ranges with a reps-left target give the same control without heavy single attempts. TrainHere’s plans work that way: you start with a load you can control, and the app progresses from what you log.

QUESTIONS

What people
ask next.

Should I test my real one-rep max?

Not to train well. Heavy single attempts need experience, a spotter or safeties, and good technique. An estimate from a set of 3 to 8 reps is enough for choosing loads.

Why is the limit 12 reps?

Estimates from long sets drift far from what people can lift once. The app uses the same limit, so the website and app agree.

Does it work for dumbbell and machine exercises?

As a rough guide. The formula was developed for barbell lifts, and machines and dumbbells differ. Compare an exercise with its own earlier estimates.

SOURCES

LeSuer et al. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. Journal of Strength and Conditioning Research 11(4), 1997 (link is a scholarly search). Equations tracked actual maxima closely but differed by exercise.
Halperin et al. Accuracy in predicting repetitions to task failure in resistance exercise: a scoping review and exploratory meta-analysis. Sports Medicine, 2022. 12 studies, 414 participants; people underpredicted reps to failure by about one rep on average, with wide variation.

General training information for healthy adults, not medical advice. Stop an exercise that causes pain and see a qualified clinician about pain that persists. Independent professional review of TrainHere’s training content is pending.

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One-rep maxcalculator.