One Rep Max Calculator
Estimate a one-repetition maximum with the Epley equation.
Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations retain full precision.
- Prediction only; individual performance varies. A single repetition uses the lifted weight directly.
Example Calculation
- Weight lifted: 60 kg
- Repetitions: 8
60 kg for 8 repetitions gives an estimated maximum of 76 kg.
Frequently asked questions
How do I use this calculator?
Enter weight lifted, repetitions. The result updates automatically. Use Reset to restore the example values.
What method does it use?
Estimated 1RM = weight × (1 + reps / 30). Prediction only; individual performance varies. A single repetition uses the lifted weight directly.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.