One Rep Max Calculator
Enter the weight you lifted and the repetitions you managed. You get the likely one rep max and a table of training weights.
This is an estimate for general information and is not medical advice. Warm up first and use a spotter for heavy lifts. You do not need to lift a true maximum to train well.
Worked examples
100 kg for 5 reps
100 kg, 5 reps
Epley 116.7 kg, Brzycki 112.5 kg
Lombardi 117.5, Mayhew 119.0, O’Conner 112.5, Wathan 116.6.
60 kg for 10 reps
60 kg, 10 reps
Brzycki 80 kg
60 x 36 / 27.
About One Rep Max Calculator
Your one rep max, or 1RM, is the heaviest weight you could lift once with good form. Testing it directly is tiring and carries risk, so most lifters estimate it from a lighter set taken close to failure. Enter the weight and the number of repetitions you managed and the page returns six published estimates with their average.
The Epley formula (1985) is weight times one plus reps divided by 30. The Brzycki formula (1993) is weight times 36 divided by 37 minus reps. Lombardi, Mayhew, O’Conner and Wathan are shown beside them. They agree closely up to about 10 reps and drift apart after that. The page then lists the weights for 50% to 100% of your estimate, which helps you plan sets by percentage. This is an estimate and not medical advice.
How to use One Rep Max Calculator
- Enter the weight you lifted and pick kilograms or pounds.
- Enter the number of clean repetitions you completed, from 1 to 30.
- Read the estimates from each formula and the average.
- Use the percentage table to choose weights for your training sets.
Common uses
- Planning a strength programme by percentage of max
- Tracking progress without maximal testing
- Comparing formulas for a heavy set of five
- Choosing a starting weight for a new cycle
Frequently asked questions
How do you calculate a one rep max?
The Epley formula multiplies the weight by one plus the reps divided by 30. Lifting 100 kg for 5 reps gives 100 x (1 + 5/30) = 116.7 kg. Brzycki gives 112.5 kg for the same set.
Which formula is the most accurate?
None is exact. Epley and Brzycki are the most used. Accuracy is best for sets of 10 reps or fewer, so use a set of 3 to 8 reps taken close to failure.
Why does the estimate change between exercises?
The formulas were built on averages across lifts. Your own strength curve differs for a squat, a bench press and a deadlift, so treat each lift separately.
Do I need to test my true max?
No. Estimating from a lighter set is lower risk and works for planning. If you do lift heavy, warm up well and use a spotter.
Is this medical advice?
No. It is an estimate and not medical advice. Speak to your GP before starting heavy lifting if you have a health condition or an injury.