How it works
Fill in the 2 fields above and One Rep Max Calculator calculates the result instantly, recalculating as you change any value. It applies the formula 1RM = weight × (1 + reps/30). The math runs locally in your browser — nothing is sent to a server.
Formula
1RM = weight × (1 + reps/30)Examples
- Weight lifted 100 kg, Reps 5 → Estimated 1RM: 116.7 kg
Frequently asked questions
How do I use the One Rep Max Calculator?
Enter your values in the 2 input fields and the result is calculated automatically as you type. Change any value to see the numbers update instantly.
What formula does the One Rep Max Calculator use?
It uses 1RM = weight × (1 + reps/30). The calculation is performed in your browser using standard, well-established math for accurate results.
Is my data private?
Yes. The One Rep Max Calculator runs entirely in your browser. Nothing you enter is uploaded, saved to a server, or shared — it never leaves your device.
Is the One Rep Max Calculator free?
Yes, it is completely free with no sign-up, no limits and no watermarks. Like every tool on health & fitness and the rest of the platform, you can use it as often as you like.
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