One Rep Max Calculator
Estimate your one-rep max from a weight and rep count using three standard strength formulas, with a table of training weights for 1 to 10 reps.
Units
Calculated in your browser. Nothing is uploaded.
| Reps | % of 1RM | Weight |
|---|---|---|
| 1 | 100% | 115.5 kg |
| 2 | 97% | 112.3 kg |
| 3 | 94% | 109.1 kg |
| 4 | 92% | 105.9 kg |
| 5Your set | 89% | 102.7 kg |
| 6 | 86% | 99.5 kg |
| 7 | 83% | 96.3 kg |
| 8 | 81% | 93.1 kg |
| 9 | 78% | 89.9 kg |
| 10 | 75% | 86.7 kg |
Percentages are a standard strength chart applied to your estimated 1RM. Use them to pick a working weight for a target number of reps.
These figures are estimates from standard formulas and vary with the exercise, technique, and how close the set was to failure. Warm up, use a spotter, and progress gradually. This is not medical or coaching advice.
How to calculate your one-rep max
Enter your set
Type the weight you lifted and the number of reps you completed, and choose kilograms or pounds.
Read your estimate
Your one-rep max appears straight away as the average of the Epley, Brzycki, and Lombardi formulas, with each formula also shown on its own.
Plan your training
Use the rep chart to see the weight for sets of 1 to 10 reps, then click Copy 1RM summary to save the full breakdown.
Why use this tool
Three formulas and their average
Your one-rep max is estimated with the Epley, Brzycki, and Lombardi equations at once, then averaged so a single outlier formula cannot skew the figure.
Weight for every rep count
A chart maps your estimated 1RM to the load for sets of 1 to 10 reps as a percentage, so you can pick a working weight for any rep target.
Kilograms or pounds
Switch between kg and lb and the estimate and the whole chart update instantly in your chosen unit.
Sensible rep guarding
Estimates are most accurate up to about 10 reps, so higher counts carry a clear accuracy note and out-of-range entries ask for a realistic set.
Runs entirely in your browser
Everything is calculated on your device as you type. Nothing you enter is uploaded, stored, or logged.
About this tool
A one-rep max, or 1RM, is the heaviest weight you can lift for a single repetition of an exercise. Testing it directly is risky and tiring, so most lifters estimate it instead from a set they can already do. Enter the weight you lifted and how many reps you managed, and this calculator returns your estimated one-rep max as you type, with no button to press. It uses three well-known equations, Epley, Brzycki, and Lombardi, and shows each result alongside their average.
The three formulas agree closely at low rep counts and drift apart as reps climb, which is why a single averaged figure is more dependable than any one equation on its own. Accuracy is best for sets of about one to ten reps; beyond that the estimate is flagged as approximate. Below the number, a chart converts your 1RM into a working weight for sets of one to ten reps using standard percentages, so you can turn a max into a plan for strength work, higher-rep training, or a warm-up ramp.
Everything is worked out on the page and nothing you enter is uploaded, stored, or logged. For the rest of your training numbers, the BMR calculator estimates the calories your body burns at rest and the TDEE calculator turns that into a daily target for cutting, maintaining, or gaining.
Frequently asked questions
- How is one-rep max calculated?
- Your one-rep max is estimated from the weight you lifted and the reps you completed. This tool runs three standard formulas, Epley, Brzycki, and Lombardi, and shows each result plus their average. All three combine weight and reps with different coefficients, and the result updates as you type.
- Which 1RM formula is most accurate?
- No single formula is best for everyone. Epley and Lombardi tend to read a little higher at moderate reps, while Brzycki reads lower. Averaging all three smooths out that spread, which is why the headline figure is the average. Seeing each formula on its own lets you judge the range rather than trusting one number.
- How many reps should I use for a good estimate?
- Estimates are most accurate for heavy sets of about one to ten reps taken close to failure. Beyond ten reps the formulas diverge and the figure is flagged as approximate. Sets above twenty reps are not estimated at all, because the result would not be meaningful; use a heavier weight for fewer reps instead.
- What are the percentages in the rep chart?
- The chart applies a standard strength percentage table to your estimated 1RM, where one rep is 100 percent and each extra rep uses a lower share of your max. It gives you a suggested working weight for any rep target from one to ten, which is handy for planning training or picking warm-up loads.
- Can I use pounds and kilograms?
- Yes. Use the units toggle to switch between kilograms and pounds. The maths is identical either way; the estimate and the whole rep chart simply display in the unit you pick.
- Is my data uploaded anywhere?
- No. Everything runs in your browser; the weight and reps you enter are never uploaded, stored, or logged.
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