One Rep Max Calculator: Estimate Your 1RM for Any Lift
Why You Don’t Need to Actually Lift Your Max
Testing a true one-rep max (1RM) is risky, especially without a spotter. Instead, use sub-maximal testing: lift a weight for multiple reps and estimate your 1RM mathematically. Most strength programmes prescribe sets as percentages of 1RM, making this estimation essential.
The Most Accurate Formula: Epley
1RM = Weight × (1 + Reps/30)
Example: Bench press 60 kg for 8 reps → 1RM = 60 × (1 + 8/30) = 60 × 1.267 = 76 kg
Training Zones Based on 1RM
| % of 1RM | Reps Range | Training Goal |
|---|---|---|
| 90–100% | 1–3 | Max strength |
| 75–85% | 4–8 | Strength + hypertrophy |
| 65–75% | 8–12 | Hypertrophy (muscle size) |
| 50–65% | 12–20 | Muscular endurance |
For the bench press example (1RM = 76 kg): hypertrophy training would use 49–57 kg for 8–12 reps. Use the 1RM calculator to find your max for any lift.