Estimate your one-rep max.
This uses the Epley formula and then maps common training percentages from the estimate.
Strength Training
1RM Calculator
Use this 1RM calculator to estimate your one-rep max and quickly see working weights for common training percentages.
How it works
How to use the 1rm calculator
1RM Calculator is built to help you estimate top-end strength from a set you have already completed safely. It works best for lifters who want practical training percentages without maxing out constantly. Instead of guessing, you can use the result as a cleaner starting point and then adjust based on what happens in real life over the next few days or weeks.
To use this calculator well, enter the weight you lifted and the reps you completed with that weight. Once you have the estimated one-rep max, compare it to your current routine, training demands, and recovery. The best number on paper is still the number you can follow consistently enough to learn from.
1RM formulas become less reliable as rep count climbs and as set quality or fatigue changes. That does not make the tool useless. It just means the output should guide your next decision instead of replacing judgment. Use the estimate to guide training, then compare it to how the weights actually move in real sessions.
FAQ
Common questions about this calculator.
Use these quick answers as a starting point, then compare the result to your real-world progress.
What does the 1rm calculator tell me?
It gives you a practical estimate that can help you make a better starting decision. You can use it to reduce guessing, then refine the plan after you track your response over time.
How accurate is the 1rm calculator?
1RM formulas become less reliable as rep count climbs and as set quality or fatigue changes The result is most useful when you treat it as an estimate, track the outcome, and adjust based on real-world feedback.
What should I do after I get my result?
Use the estimate to guide training, then compare it to how the weights actually move in real sessions. When progress is not matching the estimate, make one small adjustment at a time so you can see what actually changed.
Who is this calculator best for?
This calculator is best for lifters who want practical training percentages without maxing out constantly. It is written for regular users first, but it can still be useful for athletes who want a simple starting point before getting more detailed.
When should I recalculate?
Recalculate when one of the main inputs changes in a meaningful way, like bodyweight, training volume, pace, calories, or your goal. You can also rerun it when your progress stalls and you want a fresh checkpoint.
These estimates are for educational purposes only and are not medical advice.
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