How 1RM is estimated
A one-rep max is the heaviest weight you can lift once. Rather than testing it directly, we estimate it from a lighter set: Epley uses weight × (1 + reps/30) and Brzycki uses weight × 36 / (37 − reps). Both are most accurate under about 10 reps.
How to use it
Enter the weight you lifted and how many clean reps you completed, then pick a formula. Your estimated 1RM appears with a table of common training percentages (95%, 90%, 85% …) to plan your sets.
Frequently asked questions
- Which formula should I use?
- Epley and Brzycki give similar numbers at low reps. Try both; the truth is usually between them.
- How many reps give the best estimate?
- Sets of 2–6 reps give the most accurate estimate. Accuracy drops as reps climb above 10.
- Should I test my true 1RM?
- Maxing out is risky without experience and a spotter. Estimating from a sub-max set is safer for most lifters.
- What are the percentages for?
- Most strength programs prescribe loads as a percentage of 1RM, so the table tells you what weight to use.