Estimate your one-rep max (1RM) from a weight you can lift for several reps, using the Epley and Brzycki formulas, and get training weights for common rep ranges.
What is a one-rep max?
Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition with good form. Many strength programs prescribe training weights as a percentage of 1RM. Testing a true max is tiring and carries some risk, so estimating it from a lighter set of several reps is a popular, safer alternative.
The formulas
Epley: 1RM = weight × (1 + reps ÷ 30)
Brzycki: 1RM = weight × 36 ÷ (37 − reps)
Both are most accurate for sets of about 2 to 10 reps taken close to failure. The calculator shows both and uses their average.
Worked example
You bench press 100 kg for 5 reps:
- Epley: 100 × (1 + 5/30) = 116.7 kg
- Brzycki: 100 × 36 ÷ 32 = 112.5 kg
- Average estimate: about 114.6 kg
For a hypertrophy block at 75% of 1RM, you would train with about 86 kg for around 10 reps.
Using percentages in training
- 85% to 95%: heavy strength work, 2 to 6 reps.
- 70% to 85%: muscle building, 6 to 12 reps.
- Below 70%: technique, endurance and warm-ups.
Frequently asked questions
Why is my estimate different from my tested max?
Formulas assume an average relationship between reps and strength. Endurance-oriented lifters often do more reps at a given percentage, which can overestimate their 1RM.
How often should I re-estimate?
Every four to eight weeks, or at the start of a new training block.
Related tools
Estimates only. Lift with good form, warm up properly and use a spotter for heavy lifts. Stop if you feel pain.