1RM Calculator
Estimated 1RM
Range: 113 - 117 kg
Epley Formula
117 kg
Brzycki Formula
113 kg
What Is a One Rep Max?
A one-repetition maximum, or 1RM, is the heaviest load you can successfully complete for one repetition of a specific exercise with intended technique and range of motion.
A 1RM calculator does not directly test that maximum. Instead, it estimates it from a lighter load that you can perform for several repetitions. Estimating a max can avoid requiring a maximal single attempt solely to obtain a programming reference.
The estimate is exercise-specific. A bench-press 1RM cannot be treated as your squat, deadlift or overhead-press 1RM.
How It's Calculated
Need.fit uses two common prediction equations to estimate 1RM from submaximal sets up to 10 repetitions. The Epley equation calculates 1RM = Weight × (1 + Reps/30). The Brzycki equation calculates 1RM = Weight × 36 / (37 − Reps). Because the models rely on different mathematical relationships between load and repetitions completed, they can return slightly different values from the same set. Need.fit shows both estimates and the resulting range instead of hiding that variation. The calculator accepts up to 10 completed repetitions. As rep counts rise, fatigue, exercise selection, individual endurance and technique make a predicted maximum less reliable.
Epley: 1RM = Weight × (1 + Reps/30) | Brzycki: 1RM = Weight × 36 / (37 - Reps)
- Weight = load lifted in kilograms or pounds
- Reps = completed repetitions (1–10)
What to Do With Your Result
Treat your estimated 1RM as a programming reference, not as an instruction to immediately attempt that weight.
Use it to compare strength over time or to understand rough relative training loads for the same exercise.
Your actual performance can change with fatigue, technique, exercise variation, equipment and readiness on a given day.
Need.fit can use your training history and current plan to make the number more useful than a standalone max estimate.