OmniCalcsOne Rep Max Calculator
Estimate the most weight you can lift once, based on a recent set.
How to Use This One Rep Max Calculator
Enter the weight you lifted and the number of clean reps you completed, then choose your unit. The calculator estimates your one rep max with four widely used formulas and averages them.
- Weight lifted — a weight you can move with good form.
- Reps — how many reps you completed; 2–10 gives the most reliable estimate.
- 1RM — the estimated maximum for a single rep.
- Percentage table — working weights for common training intensities.
Practical Example
You bench press 100 kg for 5 reps:
- Epley: 100 × (1 + 5/30) ≈ 116.7 kg
- Brzycki: 100 × 36/32 = 112.5 kg
- The average of the four formulas is a sensible working estimate.
Use the estimate to set training percentages, not to attempt a true max every session.
What Your Results Mean
- 1RM — an estimate, not a guarantee. Fatigue, form and rest all change the true value.
- Formula spread — if the numbers differ a lot, your rep count was probably outside the 2–10 sweet spot.
- Training use — 70–85% of 1RM is the usual range for building strength.
Frequently Asked Questions
Which 1RM formula is most accurate?
No single formula wins for everyone. Epley and Brzycki are the most studied and agree closely for sets of 2–10 reps, which is why the average is shown.
How many reps should I use to estimate 1RM?
Two to ten reps give the best results. Very high rep sets rely on endurance and underestimate your true strength.
Should I test a real one rep max?
Only with a spotter and good technique. For most training, an estimated 1RM from a hard set is safer and accurate enough to set percentages.
Does body weight affect the estimate?
These formulas use only the weight and reps. For bodyweight exercises like pull-ups, add your body weight to any added load before entering the total.
Can I use this for any lift?
Yes, it works for bench press, squat, deadlift and most compound lifts. Isolation exercises are harder to estimate because form breaks down differently.