One rep max calculator
Enter the weight you lifted and how many reps you completed. The page shows the Epley estimate, the Brzycki estimate, their average, and a percentage table.
- Epley and Brzycki
- Free, no sign-up
This is a standard estimate to plan with. It is general information, and your doctor is the right person for medical advice.
These are standard formulas for planning. Your doctor, dietitian or pharmacist is the right person for medical advice.
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How to use it
- Enter the weight and the reps from one set.
- Choose kilograms or pounds.
- Read both estimates, the average, and the training-weight table.
Epley, Brzycki and the table
Epley is weight × (1 + reps / 30). Brzycki is weight × 36 / (37 − reps). They meet at 10 reps and sit close together for shorter sets. The table lists 50% to 100% of the average, with a typical rep range at each step, so a training weight is a percentage of that average.
A set of one rep is already a one-rep max. Above 10 reps the two formulas drift, so treat a long set as a rough guide and confirm a heavy single with a spotter when it matters. These are standard formulas for planning. Your doctor, dietitian or pharmacist is the right person for medical advice.
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Questions
What is the Epley formula?
Multiply the weight by 1 plus the reps divided by 30. Five reps at 100 kg is about 116.7 kg.
What is the Brzycki formula?
Multiply the weight by 36, then divide by 37 minus the reps. Five reps at 100 kg is 112.5 kg.
Why show both and an average?
The two formulas agree closely up to about ten reps and pull apart after that. The average is the figure the percentage table uses.
How do I use the percentage table?
Pick the percent that matches the rep range you want. 85% of the average is a heavy set of about 5 to 6 reps. 70% is closer to 11 or 12.
What if my set was more than 10 reps?
The page still calculates up to 20 reps and marks the result as less accurate. A shorter set gives a tighter estimate of a single.