One-Rep Max Calculator

A one-rep max is the maximum amount of weight you can lift for a single complete repetition of a given exercise with proper form. It's considered the gold standard for measuring absolute strength and is commonly used in powerlifting and strength training programs.

Your 1RM lets you train at specific percentages of your maximum capacity, which is essential for structured strength programming. For example, hypertrophy training typically targets 65–85% of 1RM, while maximal strength work targets 85–100%. It removes guesswork from your training.

The safest way is to perform a set of 1–10 reps with a challenging weight and then plug those numbers into a 1RM calculator. Attempting a true 1RM without an experienced spotter or coach carries injury risk, so estimation from submaximal sets is widely recommended.

All three formulas are reasonably accurate when reps are kept between 1 and 10. Epley is the most widely used and performs well across a broad rep range. Brzycki tends to be slightly more conservative, while Lander can be more accurate for lower-rep sets. Differences between them are generally small.

For the best accuracy, use a weight you can lift between 1 and 10 reps. The further you go above 10 reps, the less precise the estimate becomes because fatigue and muscular endurance start to play a larger role relative to pure strength.

No. Your 1RM is exercise-specific. Your bench press 1RM will be very different from your squat or deadlift 1RM, and even close variations like a close-grip bench press vs. a standard bench press can produce different maxes. Always calculate 1RM separately for each lift you track.

Most strength coaches recommend reassessing your 1RM every 4–8 weeks, or at the end of a training cycle. As your strength improves, your training percentages should be updated accordingly to keep your workouts appropriately challenging.

Yes, but with caution. Beginners should avoid actual maximum-effort single-rep attempts, which carry a higher injury risk without developed technique. Using the calculator with a submaximal set of 5–8 reps gives a safe and useful estimate while building a baseline to track progress over time.