1RM Calculator
Estimate your one-rep max using 7 formulas + training percentages.
See how it works
Watch a quick simulation of this tool in action — no file needed.
How to use 1RM Calculator
Follow these steps — everything happens instantly in your browser.
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Step 1. Enter the weight you lifted in kilograms.
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Step 2. Enter the reps performed (1–15).
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Step 3. Pick a formula (or compare across all seven).
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Step 4. Read your estimated 1RM and the training percentages.
Why use this tool
Frequently asked questions
Everything you might want to know about 1rm calculator.