One Rep Max Calculator

Your one rep max (1RM) is the maximum amount of weight you can lift for a single complete repetition of a given exercise while maintaining proper form. It is the gold standard measurement of maximal strength in powerlifting, bodybuilding, and general strength training.

Using our one rep max calculator, you can estimate this value safely without performing a potentially dangerous maximal lift. Simply enter the weight you can lift for multiple reps, and our 1RM calculator applies validated scientific formulas to predict your one-repetition maximum for exercises like bench press, squat, deadlift, and overhead press.

To calculate 1 rep max safely, choose a weight you can lift for 3-10 reps with proper technique. The fewer reps you perform, the more accurate the estimate. Our 1RM calculator uses five peer-reviewed formulas:

• Epley Formula: 1RM = W × (1 + R/30) — The most popular and practical formula for general training.
• Brzycki Formula: 1RM = W × 36/(37 − R) — Slightly more conservative, commonly used in academic research.
• Lombardi Formula: 1RM = W × R^0.10 — Tends to estimate higher for lower rep ranges.
• Lander Formula: 1RM = 100W / (101.3 − 2.67123R) — Developed for competitive powerlifters.
• Mayhew Formula: 1RM = 100W / (52.2 + 41.9e^−0.055R) — Accounts for nonlinear fatigue patterns.

W = weight lifted in kg, R = number of reps performed. For the best estimate, many coaches recommend averaging multiple formulas. Our estimated one rep max calculator does this automatically.

RPE stands for Rate of Perceived Exertion, a scale popularized by Mike Tuchscherer that measures how hard a set feels. On the 1-10 RPE scale, 10 means you could not have completed another rep, 9 means you had one rep left in reserve, 8 means two reps left, and so on.

Our one rep max calculator with RPE allows you to adjust your estimate based on how close to failure you actually were. If you did 80 kg for 5 reps at RPE 9 (one rep left), your true max effort for 5 reps would be higher — and so would your estimated 1RM. This makes our tool the most nuanced 1RM calculator available for serious lifters.

Once you know your estimated one rep max, you can structure your training intensity:

• Strength (85-100% of 1RM): 1-5 reps per set. Builds neural adaptation and maximal strength.
• Hypertrophy (67-85% of 1RM): 6-12 reps per set. Stimulates muscle growth and size.
• Endurance (50-67% of 1RM): 12-20+ reps per set. Improves muscular stamina and capillary density.

Our one rep max calculator bench press and other exercise-specific estimates provide the training percentages you need to plan effective, targeted workouts. Use the percentage table in the results section to find the right working weight for your goal.

Your 1RM calculator estimates the weight for a single rep, but you can also calculate your rep max for any number of reps. For example, your 5RM is the maximum weight you can lift for 5 reps. Using our tool as a rep max calculator, you can work backward: enter any weight and rep count to estimate what the equivalent 1RM would be, then use the reverse calculation to find the weight for any target rep range.

This is especially useful for programs like 5x5 training, where you need to know the precise weight for sets of 5. Our 5x5 one rep max calculator approach makes it easy to plan your working sets.