Epley Formula

Predicting a true 1-rep max without actually performing it helps mitigate injury risk. We use the Epley formula, widely considered the most accurate method for compound lifts:

1RM = Weight × (1 + Reps / 30)

Note: Predictions become less accurate the higher the rep count. Inputs beyond 10-12 reps may yield an inflated estimated max.

Frequently Asked Questions

Is the One-Rep Max Calculator free to use?

Yes, the One-Rep Max Calculator is 100% free to use. There are no subscriptions, no sign-ups, and no hidden fees.

Is my data safe when using the One-Rep Max Calculator?

Absolutely. All calculations performed by the One-Rep Max Calculator happen locally in your web browser. We do not store, track, or transmit your inputs or results to any server.

How accurate is the One-Rep Max Calculator?

Our One-Rep Max Calculator uses industry-standard formulas and methodology. You can view the exact formula and calculation logic used in the methodology section above to verify the math yourself.

Can I use the One-Rep Max Calculator on my mobile phone?

Yes! The One-Rep Max Calculator is fully responsive and works seamlessly on all devices including smartphones, tablets, and desktop computers.