One Rep Max (1RM) Calculator

How to Use One Rep Max Calculator

1. Enter the weight you lifted. Type the weight in kilograms that you successfully lifted with good form.
2. Enter the number of reps. Input how many times you lifted that weight (between 2 and 12 reps). The tool needs at least 2 reps for a valid estimate.
3. Click Calculate. The calculator applies the Epley and Brzycki formulas, then averages them to give your estimated one‑rep max.
4. Use the training table. Scroll down to see how much weight you should lift at different percentages of your 1RM, along with typical rep ranges for each intensity.

Benefits of One Rep Max Calculator

• Estimates your maximum lift without the injury risk of attempting a true 1RM, especially important for beginners.
• Uses two different formulas (Epley and Brzycki) and averages them for a more reliable number than either formula alone.
• Generates a full percentage‑based training table so you can plan strength, hypertrophy and endurance sets without mental math.
• Works entirely offline – your training data stays on your device.

Frequently Asked Questions

How accurate is the one rep max estimate?

For reps between 3 and 10, the estimate is usually within 5% of your true 1RM. Accuracy drops for very high rep sets (12+) or if the weight used was not near your maximum effort for that rep count.

Can I use this calculator for any exercise?

It works best for compound lifts like bench press, squat and deadlift. For isolation exercises like bicep curls, the formulas still give a reasonable estimate, but real‑world accuracy may vary slightly.

Should I test my true 1RM regularly?

Most coaches recommend testing only every 8‑12 weeks. Frequent maximal attempts increase injury risk and can stall progress. Use the calculated estimate to set training loads between tests.

Is One Rep Max Calculator free and private?

Yes — it is 100% free, needs no sign‑up, and everything runs in your browser; your data never leaves your device.