One-rep max calculator
Enter the weight and the reps from a hard set and get your estimated one-rep max from three formulas, their average, and a chart of the weights to use at each training percentage.
– kg
Estimated one-rep max (average of three formulas)
Training weights
| % of 1RM | Weight | Typical reps |
|---|
Three formulas
Strength coaches have published many ways to predict a one-rep max (1RM) from a set of several reps. This calculator shows three of the most used and averages them:
- Epley: 1RM = weight × (1 + reps ÷ 30).
- Brzycki (1993): 1RM = weight × 36 ÷ (37 − reps).
- Lombardi: 1RM = weight × reps0.10.
They agree closely at low reps and spread apart as reps climb, which is why the calculator caps the input at 12. Past that point endurance, not maximal strength, decides how many reps you get.
Using the percentage chart
Programs are often written in percentages of 1RM: heavy strength work around 80–90%, typical hypertrophy work around 65–80%, technique and warm-ups lower. The reps column is a guide to what most people can do at each percentage; your own numbers will vary by exercise and training history. Re-test with a fresh hard set every few weeks rather than chasing a true single.
Strength and your calories
Lifting burns less than people expect: the 2024 Compendium rates typical weight training at 3.5 to 6 METs depending on effort. Its bigger effect on daily energy is the muscle it helps you keep while you eat less. Add your sessions in the TDEE calculator and use the workout planner for a weekly structure.