Knowing your one-rep max lets you program training with precision. Instead of guessing weights, you work at deliberate percentages that target strength, hypertrophy or power.
Why estimate instead of test?
Testing a true 1RM is fatiguing, technically demanding and carries injury risk. Estimating from a set of 3–8 reps gives nearly the same information with far less cost to recovery.
The formulas
The two most common are Epley: 1RM = w × (1 + r/30), and Brzycki: 1RM = w × 36/(37 − r). We average them for a balanced estimate that holds up across the low-rep range.
Using your percentages
Strength work lives at 85–100% for 1–5 reps; hypertrophy at 65–80% for 8–12 reps; power and speed at 50–70% moved explosively. Rotate these to drive continued progress.
Frequently asked questions
It's the maximum weight you can lift for a single, full repetition of an exercise. It's the reference point for programming strength training by percentage.
We average the Epley (weight × (1 + reps/30)) and Brzycki (weight × 36/(37−reps)) formulas, which predict your max from a submaximal set. Accuracy is best at 1–8 reps.
Every 4–6 weeks is plenty. You don't need to lift a true single — a hard set of 3–5 reps run through this calculator gives a reliable, lower-risk estimate.