One-Rep Max Calculator
What's my
estimated 1RM?
Enter the weight and reps you just lifted to estimate your one-rep max (1RM).
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1RM Ledger
Results update instantly as you type
Estimated 1RM
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Training Weight (80%)
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How is this calculated?
We use the widely-used Epley formula: "1RM = weight × (1 + reps ÷ 30)". Accuracy decreases past about 10 reps, so estimates from 1-10 rep sets tend to be more reliable.
Why show 80%?
Many strength and hypertrophy programs train at 70-85% of 1RM. The 80% figure gives you a useful reference point for planning today's training weight.
Frequently Asked Questions
How accurate is this result?
It's a well-established estimation formula, but actual 1RM varies by individual and exercise.
Is my data stored or sent anywhere?
No. All calculations happen entirely in your browser.
Does this work on mobile?
Yes, the layout automatically adapts to your screen size.