One Rep Max Calculator
Calculate your estimated 1-rep max from any weight and rep combination. Get training percentages for strength programs.
Last updated: February 2026
How this calculator is verified
Checked by True Calculator automated test suite on
- Formula verified against a published worked example in the automated test suite
- Edge cases (zero, negative, boundary and unit-mismatch inputs) covered by unit tests
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When to Use This Calculator
Strength training programmes are built around percentages of your one-rep max (1RM), but testing a true 1RM every week is risky and tiring. This calculator estimates it from a lighter set using the Epley formula: weight lifted × (1 + reps/30). If you bench press 60 kg for 10 reps, your estimated 1RM is about 80 kg, and every working set can be planned as a percentage of that. Gym-goers in India use it before starting a new programme, to track progress month over month, and to decide sensible weights for squats, deadlifts and overhead presses. Beginners should keep several reps in reserve; the estimate assumes near-maximum effort, so it is safer to underestimate than to chase the number. Re-testing every 8–12 weeks with the same weight and rep scheme gives a clean progress trend.
How to Use This Calculator
- Step 1: Enter the weight you lifted, in kilograms, for a set you can complete with clean form.
- Step 2: Enter the number of reps you managed in that set, ideally between 2 and 12.
- Step 3: Calculate and read your estimated one-rep max, based on the Epley formula.
- Step 4: Read the training table showing percentages of that max with recommended rep counts for each.
Worked Example
A lifter in Gurugram who benches 60 kg for 10 clean reps enters 60 as the weight and 10 as the reps. The Epley formula estimates a one-rep max of 60 times 1.33, or about 80 kg. The calculator then shows training percentages, so 70 percent of the max is 56 kg and 80 percent is 64 kg, each with a suggested rep count. Heavier loads around 85 percent suit sets of a few reps, while lighter loads around 65 to 70 percent suit higher-rep volume work.
Tips and Common Mistakes
- •Tip 1: Use a weight you can lift with good form; a wobbly set inflates the estimate and misleads your training numbers.
- •Tip 2: Use the percentage table to plan cycles, such as 3 sets of 5 at 85 percent one week and higher-rep work at 70 percent the next.
- •Tip 3: Re-test every four to six weeks, since the estimate drifts as your strength improves.
- ✗Mistake 1: Testing a true one-rep max without a spotter; the estimate from a 5 to 10 rep set is safer and close enough for programming.
- ✗Mistake 2: Entering the total weight including the bar as one number when the field expects the load you actually lifted.
Frequently Asked Questions
What is a one-rep max?
It is the heaviest weight you can lift for a single repetition with proper form. The calculator estimates it from a set you can actually complete, so you never need to attempt a risky max-effort single.
How is the one-rep max estimated?
The Epley formula estimates it as weight × (1 + reps ÷ 30). Lifting 60 kg for 10 clean reps gives 60 × 1.333, or an estimated max of about 80 kg.
What rep range gives the best estimate?
Sets of 2 to 12 reps work well. Lower-rep sets give a slightly more accurate estimate but use heavier loads, while higher-rep sets are safer to attempt alone — the calculator accepts any set done with consistent effort and good form.
Is it safe to test a true one-rep max?
Max-effort singles carry a higher injury risk, especially on lifts like the bench press without a spotter. The estimate from a 5–10 rep set is safer and close enough for programming your training.
How should I use my estimated max in training?
Use the percentage table: heavier loads around 85% of your max suit sets of a few reps, while loads around 65–70% suit higher-rep volume work. Re-test every four to six weeks, since the estimate drifts as you get stronger.
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