How the bench max is estimated
The more reps you can do with a weight, the lighter it is compared with your true max. One rep max formulas turn that relationship into a number. This calculator shows three of the most used ones:
- Epley: weight times (1 plus reps divided by 30)
- Brzycki: weight times 36, divided by (37 minus reps)
- Lombardi: weight times reps raised to the power of 0.10
For example, 185 lb for 5 reps gives about 216 lb with Epley and 208 lb with Brzycki. The headline number uses Epley. If you enter a single rep, your max is simply the weight you lifted.
Getting a reliable estimate
Use a set of 2 to 10 reps taken close to failure with good form: full range, a touch on the chest and no bounce. Estimates from sets above 10 reps drift, because muscular endurance starts to matter more than strength.
Using the training table
The table turns your max into working weights, rounded to the nearest 5 lb or 2.5 kg. As a rough guide, 85% and above builds maximal strength with low reps, 65 to 80% is the usual range for muscle growth, and 60% suits technique work and warm-ups.
The same formulas work for squat, deadlift and overhead press.
Common questions
How accurate is a one rep max calculator?
For sets of 2 to 10 reps, most people land within about 5% of their true max. Accuracy drops with higher reps and varies between lifters.
Which one rep max formula is best?
Epley and Brzycki are the most widely used and agree closely under 10 reps. Epley tends to read slightly higher. Comparing two or three formulas gives you a realistic range.
Should I test my true one rep max?
You do not need to for training. An estimate from a hard set of 3 to 5 reps is enough to set working weights and carries less injury risk. If you do test, use a spotter or safety bars.
How often should I recalculate?
Whenever you beat a previous rep best with the same weight, or every 4 to 8 weeks at the end of a training block.