Which formula is most accurate?

No single formula is universally best. The Epley and Brzycki formulas tend to be most accurate for sets of 3 to 10 reps. Accuracy drops significantly above 10 reps because fatigue plays a larger role.

What rep range gives the best estimate?

Sets of 3 to 6 reps typically yield the most accurate 1RM predictions. Sets over 10 reps introduce more error because they test muscular endurance as much as strength.

Should I ever attempt an actual 1RM?

Only with proper warm-up, a spotter, and solid technique. Beginners should rely on estimated 1RM values rather than testing their true max, as the risk of injury outweighs the benefit for most training goals.

How do I use 1RM for programming?

Most strength programs prescribe work sets as a percentage of 1RM. Hypertrophy work typically falls in the 65-80% range for 6-12 reps, while strength work sits at 80-95% for 1-5 reps.

How often does my 1RM change?

Your estimated 1RM can increase within weeks of consistent training, especially for beginners. Recalculate every 4 to 8 weeks as you progress to keep your training percentages accurate.

Health

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One Rep Max Calculator

Estimate your one rep maximum (1RM) for any lift using popular formulas. Calculate training percentages for different rep ranges.

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How to use this calculator

👉 Fill in the boxes below and your answer appears instantly — no maths needed, we do it all for you! 🎉

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In plain English — what does this do?

💚 A body helper! It tells you things about your health — like how much food you need, a healthy weight for your height, or when a baby might arrive. Easy to use, no doctor needed!

📌 Direct Answer & Summary

Your one rep max (1RM) is the maximum weight you can lift for a single repetition of a given exercise with proper form. It is the standard benchmark for measuring strength in powerlifting and resistance training. Because attempting a true 1RM can be risky, this calculator estimates it from a submaximal set using proven formulas.

Weight lifted

Reps completed

What is One Rep Max Calculator?

How to use it

1️⃣ Enter the weight you lifted in your working set.
2️⃣ Select kilograms or pounds depending on your equipment.
3️⃣ Enter the number of reps you completed with that weight.
4️⃣ The calculator returns your estimated 1RM using the Epley, Brzycki, and Lander formulas.
5️⃣ Use the training percentages table to plan your programming at 50% to 100% of your estimated max.

Formula

Epley: 1RM = Weight x (1 + Reps / 30) | Brzycki: 1RM = Weight x 36 / (37 - Reps)

💡 See it in action — a real example

If you lifted 80 kg for 8 reps, the Epley formula gives 80 x (1 + 8/30) = 101.3 kg. The Brzycki formula gives 80 x 36 / (37 - 8) = 99.3 kg. The average across all three formulas would be your most reliable estimate.

❓ Common questions

Which formula is most accurate?: No single formula is universally best. The Epley and Brzycki formulas tend to be most accurate for sets of 3 to 10 reps. Accuracy drops significantly above 10 reps because fatigue plays a larger role.
What rep range gives the best estimate?: Sets of 3 to 6 reps typically yield the most accurate 1RM predictions. Sets over 10 reps introduce more error because they test muscular endurance as much as strength.
Should I ever attempt an actual 1RM?: Only with proper warm-up, a spotter, and solid technique. Beginners should rely on estimated 1RM values rather than testing their true max, as the risk of injury outweighs the benefit for most training goals.
How do I use 1RM for programming?: Most strength programs prescribe work sets as a percentage of 1RM. Hypertrophy work typically falls in the 65-80% range for 6-12 reps, while strength work sits at 80-95% for 1-5 reps.
How often does my 1RM change?: Your estimated 1RM can increase within weeks of consistent training, especially for beginners. Recalculate every 4 to 8 weeks as you progress to keep your training percentages accurate.

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