One-rep max calculator
Enter the weight you lifted and how many reps you managed: get your estimated maximum with seven recognised formulas, and the loads to train at each percentage.
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Your set
Clean reps in a single set, taken close to failure.
The smallest step your plates allow, both sides of the bar together.
Estimating from a set of 10 reps or fewer is safer than testing your true maximum. If you do test it: warm up first, use a spotter or safety bars, and don’t attempt a maximum without a coach if you’re new to lifting.
Estimated one-rep max
— kg
Enter the weight and the number of reps to estimate your maximum.
- Range of the 7 formulas
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- In pounds
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- Your set, as a share of this maximum
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Above 10 reps, these formulas become much less reliable and disagree more. For a better estimate, use a weight you can lift 10 times or fewer.
With a single rep, the weight you lifted is your maximum: no formula is needed.
The 7 formulas
- Epley (1985) w × (1 + r ÷ 30) —
- Brzycki (1993) w × 36 ÷ (37 − r) —
- Lombardi (1989) w × r0.10 —
- O’Conner et al. (1989) w × (1 + 0.025 × r) —
- Lander (1985) 100 × w ÷ (101.3 − 2.67123 × r) —
- Mayhew et al. (1992) 100 × w ÷ (52.2 + 41.9 × e−0.055 × r) —
- Wathan (1994) 100 × w ÷ (48.8 + 53.8 × e−0.075 × r) —
w = weight lifted, r = reps.
These seven equations were compared by LeSuer et al. (1997) in the Journal of Strength and Conditioning Research.
Training loads
| % of 1RM | Load | Estimated reps |
|---|---|---|
| 100% | — | — |
| 95% | — | — |
| 90% | — | — |
| 85% | — | — |
| 80% | — | — |
| 75% | — | — |
| 70% | — | — |
| 65% | — | — |
| 60% | — | — |
| 55% | — | — |
| 50% | — | — |
Loads appear here once your maximum is estimated.
How it works
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Enter a recent set
Type the weight you lifted and the number of clean reps you completed, close to failure. Choose kilograms or pounds.
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Read your estimated maximum
The main figure is the average of seven published formulas. Each formula’s own result is listed, so you can see how far they agree.
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Plan your training loads
The table turns your maximum into loads from 50 to 100%, rounded to the plates you have, with the reps you can expect at each one. Copy it into your notes or a spreadsheet.
Frequently asked questions
How is a one-rep max estimated?
Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Instead of testing it, you can estimate it from a set taken close to failure: the more reps you manage with a weight, the further that weight is below your maximum. For 100 kg lifted 5 times, Epley gives 100 × (1 + 5 ÷ 30) = 116.7 kg and Brzycki gives 100 × 36 ÷ 32 = 112.5 kg. The calculator shows the average of seven formulas: 115.5 kg.
Where do the seven formulas come from?
Each one was published by strength coaches or researchers: Epley (1985, Boyd Epley Workout), Brzycki (1993, Journal of Physical Education, Recreation & Dance), Lombardi (1989, Beginning Weight Training), O’Conner, Simmons and O’Shea (1989, Weight Training Today), Lander (1985, National Strength and Conditioning Association Journal), Mayhew et al. (1992, Journal of Applied Sport Science Research) and Wathan (1994, in Essentials of Strength Training and Conditioning). LeSuer et al. compared all seven in 1997.
Which formula is the most accurate?
None is best for everyone. When LeSuer et al. (1997) compared them with measured maximums, most came close for the bench press and the squat when the set had fewer than 10 reps, and they were less accurate for the deadlift. Results also depend on the exercise, your training and how close to failure you went. That is why the calculator gives the average and shows the range of the seven.
Why is the estimate less reliable above 10 reps?
A long set depends more on muscular endurance than on maximal strength, and endurance varies a lot from one person to another. The formulas were built from short sets, so they drift apart as reps go up: at 10 reps, the highest estimate is about 8% above the lowest; at 15 reps, about 25%. For the best estimate, use a weight you can lift between 3 and 10 times.
Is it safe to test my real one-rep max?
A true maximum is a demanding effort. Warm up with several lighter sets first, use a spotter or the safety bars of a rack, and keep your technique strict. If you are new to lifting, build your technique for a few months and test a maximum only with a qualified coach. If you have a heart condition, high blood pressure, an injury or are pregnant, ask a doctor before heavy lifting. An estimate from a submaximal set is often all you need.
Are my numbers stored?
No. The calculation runs in your browser and nothing is sent anywhere. Only your choice of kilograms or pounds is remembered on this device.