Bench press set
Input
225 lb × 5 reps
Expected result
Epley 262.5 lb; Brzycki 253.1 lb; average 257.8 lb
Calculators
One Rep Max Calculator
Estimate your one-rep max from a submaximal set with the Epley and Brzycki formulas.
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About this tool
Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Testing it directly is tiring and carries more risk, so lifters often estimate it from a set of several reps. Enter the weight you lifted (in pounds or kilograms) and the reps you completed, from 1 to 15, and this 1 rep max calculator applies two widely used formulas: Epley, weight × (1 + reps ÷ 30), and Brzycki, weight × 36 ÷ (37 − reps). It shows both results and their average. A single rep is treated as your 1RM. Below the estimate, a training chart lists 100% down to 50% of the average 1RM with the weight to load and the approximate reps that percentage allows by the Epley formula. Estimates are most reliable from sets of 10 reps or fewer taken close to failure, and the tool notes when you go higher. It works for any lift and runs in your browser.
Why use it
Two formulas side by side: Epley and Brzycki, plus their average.
Training chart from 50% to 100% of your estimated max, with approximate reps.
Pounds or kilograms, for any barbell, dumbbell or machine lift.
No max-out needed: estimate from a normal working set.
Free and private, with nothing stored.
How to use
- Enter the weight you lifted and choose lb or kg.
- Enter how many reps you completed with good form (1 to 15).
- Read the Epley, Brzycki and average one-rep max estimates.
- Use the percentage chart to pick training weights for your programme.
When it helps
- Setting percentage-based weights for a strength programme.
- Tracking strength progress between training blocks without testing a true max.
- Estimating your bench press, squat or deadlift max from a recent set.
- Choosing a starting weight for a new rep range.
Examples
Ten-rep set
Input
100 kg × 10 reps
Expected result
Epley and Brzycki both 133.3 kg
Single
Input
315 lb × 1 rep
Expected result
1RM 315 lb
Tips
- Use a set taken close to failure; stopping well short of failure underestimates your max.
- Re-estimate every few weeks so training percentages keep up with your progress.
- Round training weights to the plates you have available.
Frequently Asked Questions
How do you calculate a one-rep max?
Lift a weight for as many good reps as you can, then apply a formula. With Epley, 225 lb for 5 reps gives 225 × (1 + 5 ÷ 30) = 262.5 lb. With Brzycki it gives 225 × 36 ÷ 32 = 253.1 lb.
Which formula is more accurate?
Neither is exact for everyone. Both agree at 10 reps and are close below that; Brzycki gives lower estimates for low-rep sets. The average is a reasonable middle ground.
Why is the limit 15 reps?
The formulas were built around lower rep ranges and drift apart as reps increase, and Brzycki breaks down near 37 reps. The calculator accepts up to 15 and warns above 10.
What if I only did one rep?
Then the weight you lifted is your one-rep max, and both formulas return it unchanged.
How are the reps in the percentage chart estimated?
They come from rearranging the Epley formula: reps ≈ 30 × (100 ÷ percentage − 1). For example 80% of 1RM corresponds to about 8 reps. Individual results vary with the lift and training history.
Is it safe to test a true one-rep max?
Max attempts carry more risk than submaximal sets. Use a spotter or safety arms, warm up thoroughly, and stop if form breaks down. If you have an injury or health condition, ask a qualified professional first.
Explore the category
Glossary
- 1RM
- One-repetition maximum: the most weight you can lift once.
- Epley formula
- 1RM = weight × (1 + reps ÷ 30).
- Brzycki formula
- 1RM = weight × 36 ÷ (37 − reps).
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