Your training percentages
Most strength programs set working weights as a percentage of your 1RM. This chart updates with your estimate and shows roughly how many reps you can do at each load, based on the NSCA percentage chart.
| % of 1RM | Weight | Reps (approx.) |
|---|---|---|
| 100% | 116.7 kg | 1 |
| 95% | 110.8 kg | 2 |
| 90% | 105 kg | 4 |
| 85% | 99.2 kg | 6 |
| 80% | 93.3 kg | 8 |
| 75% | 87.5 kg | 10 |
| 70% | 81.7 kg | 11 |
| 65% | 75.8 kg | 15 |
How do you calculate a one-rep max?
Your one rep max (1RM) is the heaviest weight you can lift for a single rep with good form. Testing it directly is tiring and risky, so most lifters estimate it from a hard set of several reps. Enter the weight and reps from that set and the calculator applies three well-known formulas:
- Epley: 1RM = weight × (1 + reps ÷ 30)
- Brzycki: 1RM = weight × 36 ÷ (37 − reps)
- Lombardi: 1RM = weight × reps0.10
For example, 100 kg for 5 reps gives an estimated 1RM of 116.7 kg with Epley, 112.5 kg with Brzycki and 117.5 kg with Lombardi. In pounds, 225 lb for 5 reps gives 262.5 lb, 253.1 lb and 264.3 lb.
The same formulas work for the squat, bench press, deadlift and overhead press. Use a set from the lift you want to estimate, because your max on one lift tells you little about another.
The formulas agree closely at low reps and drift apart as reps rise, so the calculator stops at 12 reps. A single rep is your 1RM, so it's returned as entered.
Questions
How accurate is an estimated 1RM?
Estimates are most accurate from heavy sets of about 2–6 reps taken close to failure. They get less reliable as reps rise and vary between lifters and exercises, so treat the number as a guide, not a guarantee.
Which formula should I use?
Epley is the most widely used and a good default. Below 10 reps, Brzycki gives a slightly lower estimate; Lombardi runs a little higher at low reps and lower at high reps. Pick one and stick with it so your numbers stay comparable over time.
Should I test my true 1RM?
Only if you're experienced, fully warmed up, and lifting with a spotter or safety bars. For most training, an estimated max is enough to set your working weights.
Can FitJot track my 1RM for me?
Yes. The FitJot workout tracker detects personal records automatically as you log your sets, shows strength and volume trends, and includes this 1RM calculator. Estimated 1RM trend charts are part of FitJot Plus. Need to load the bar? Use the plate calculator, and plan your ramp with the warm-up calculator.