Enter your weight lifted and the number of reps you completed for that weight, then choose your unit (pounds or kilograms). The calculator applies two well-established formulas—Epley and Brzycki—to estimate your one-rep max from that single submax set. It averages the two estimates to reduce bias toward either formula, then generates a complete percentage chart (50–95% of your estimated 1RM) to help you plan working sets across different rep ranges and training goals.
Accuracy is best for sets of 2–10 reps and can vary by ±5–10% depending on your experience level and lifting technique. Beginners may see wider variation; advanced lifters tend to be more consistent.
Epley and Brzycki were developed independently and use different mathematical assumptions. Epley is more conservative and works well for lower rep counts; Brzycki tends to predict slightly higher maxes. Averaging them reduces the risk of significant over- or under-estimation.
Training intensity depends on your goal. 80–90% is typical for strength work (1–6 reps), 70–80% for hypertrophy (6–12 reps), and 50–70% for endurance and recovery work. Most programs use a mix across different sessions.
Testing a true 1RM is useful for baseline data and motivation, but it's taxing and carries injury risk. Most strength programs rely on estimated 1RMs for daily training and reserve true max testing for occasional checkpoints (every 3–6 months).
These formulas were calibrated using data from lower-rep sets where strength (not fatigue or metabolic demand) is the limiting factor. Above 10 reps, fatigue, form breakdown, and individual conditioning become much more variable, reducing the reliability of any single-formula estimate.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.