One Rep Max Calculator
Estimate your 1RM from any set of 1–12 reps using the Epley, Brzycki and Lombardi formulas, with training percentages.
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Quick Tip
Enter the weight you lifted and the number of clean repetitions you completed.
About This Tool
Why use One Rep Max Calculator?
This one-rep max calculator estimates the heaviest weight you could lift for a single repetition, based on a set you have already completed. It runs three established formulas — Epley, Brzycki and Lombardi — and averages them, then builds a table of training weights from 60% to 100% of that maximum.
Example: 100 kg for 5 reps. Epley gives 116.7 kg, Brzycki gives 112.5 kg and Lombardi gives 117.5 kg, averaging about 116 kg. From there, a set at 80% of your max is roughly 92 kg, which is the kind of number most programmes are written around.
Key Benefits
Three formulas, one average
Epley, Brzycki and Lombardi each behave differently across rep ranges, so averaging them is more robust than trusting any single one.
Training percentages included
A full table from 100% down to 60% of your max, which is what strength programmes are actually written in.
Safer than testing
Estimating from a set of 3–5 reps avoids the injury risk and central nervous system fatigue of a true max attempt.
How to use One Rep Max Calculator
- 1
Enter the weight you lifted and the number of clean repetitions you completed.
- 2
Use a set between 1 and 12 reps — accuracy falls away sharply above about 10.
- 3
Compare the three formula estimates; a wide spread means the rep count was high.
- 4
Use the percentage table to set working weights for your programme.
Best use cases
Set working weights for a percentage-based programme such as 5/3/1.
Track strength progress without repeatedly testing a true max.
Estimate a max for a lift you have never tested singly.
Pick an appropriate opener for a powerlifting meet.
How this tool compares
One Rep Max Calculator FAQs
How accurate is a one-rep max calculator?
Estimates from sets of 3–5 reps are usually within a few percent of a true max. Accuracy degrades as reps rise, because sets of 10 or more depend heavily on muscular endurance and pain tolerance, which vary far more between people than maximal strength does.
Which formula is best?
Brzycki tends to read lower at higher rep counts and Epley higher, with Lombardi between them. Rather than picking one, use the average, and note that a large spread between the three is itself a signal that your rep count was too high for a reliable estimate.
Does this work for every lift?
It works best for compound barbell lifts such as the squat, bench press, deadlift and overhead press, where the rep-to-max relationship is well established. Isolation exercises and machines are less predictable, and deadlifts often estimate slightly high because they fatigue quickly at high reps.
How often should I test my max?
Most lifters rarely need to. Estimating from working sets every few weeks gives you the same information without the fatigue cost, and a true max test every few months — or only before a competition — is plenty for tracking progress.
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