Fitness calculator
One-Rep Max Calculator
Estimate maximum strength without performing a true one-rep test.
Uses the Epley estimate. Best suited to controlled sets of 1–10 repetitions; do not exceed safe loads.
Estimated one-rep max
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How it works
The Epley equation is an estimate and becomes less reliable at high rep counts. Use safe technique and appropriate supervision.
Estimated 1RM = weight × (1 + reps ÷ 30)
Worked example
Lifting 100 units for 5 reps gives an estimated 116.67-unit one-rep max.
How to use this tool
- Enter the known values and choose units where available.
- Check the primary result and supporting details.
- Clear or replace an input to calculate another case.
Frequently asked questions
What happens with invalid or incomplete inputs?
The result remains blank until the required inputs form a finite, meaningful calculation. Zero denominators and physically impossible negative quantities are not calculated.
Can I use decimal values?
Yes. The tool accepts decimals and keeps full precision for the calculation while rounding the displayed result for readability.