Estimate your one-rep maximum (1RM) from any weight and rep count using 7 established formulas. Get a complete percentage-based training weight table — from 50% to 100% of your 1RM — to program your workouts with precision.
Your 1RM Estimate
Estimated 1RM (Epley)—
Formula Average—
Weight Used—
% of Estimated 1RM—
Why 1RM Matters for Training
Your one-rep maximum is the foundation of percentage-based strength programming. Instead of guessing what weight to use, you calculate exact training loads as fractions of your max. This ensures you're training at the right intensity for your specific goal — strength, hypertrophy, or endurance.
The 7 Formulas
Each formula was derived from different populations and methodologies. Epley (1985): 1RM = weight × (1 + reps/30). Brzycki (1993): 1RM = weight × 36/(37-reps). McGlothin (1989): 100 × weight / (101.3 - 2.67123 × reps). Lombardi (1989): weight × reps^0.10. Mayhew (1992): 100 × weight / (52.2 + 41.9 × e^(-0.055×reps)). O'Conner (1989): weight × (1 + 0.025 × reps). Wathan (1994): 100 × weight / (48.8 + 53.8 × e^(-0.075×reps)). Average these for the most reliable single estimate.
Percentage-Based Training
Classic strength programs use these intensity zones: 90–100% 1RM for maximal strength (1–3 reps, CNS adaptation). 75–89% for strength-hypertrophy overlap (4–6 reps). 65–74% for hypertrophy (8–12 reps). 50–64% for muscular endurance (15–30 reps) and technique work. Most powerlifting and Olympic lifting programs prescribe specific percentages per set.
Testing vs. Estimating 1RM
Formulas are most accurate at 1–5 reps. Above 10 reps, accuracy drops significantly (individual variation in muscular endurance affects results). For important programming decisions, test an actual 1RM or 3RM after a thorough warm-up. Use these estimates for day-to-day programming adjustments between formal tests.
Most accurate at 1–5 rep sets (±3–5% error). Above 10 reps, accuracy drops to ±10–15% because endurance capacity varies widely between individuals. Use the average of multiple formulas for the best estimate.
65–80% of 1RM (roughly 8–15 rep range) is the classic hypertrophy zone. Recent research suggests a broader range — any load taken close to failure (within 3–5 reps of failure) produces similar muscle growth, from 30% to 85% 1RM. Volume (total sets × reps) matters most.
5/3/1 uses a "training max" of 90% of your estimated 1RM. Week 1: 65%/75%/85% of training max. Week 2: 70%/80%/90%. Week 3: 75%/85%/95%. Week 4: deload at 40%/50%/60%. Add 5 lbs to upper body training max and 10 lbs to lower body training max each cycle.
Yes with proper precautions: thorough warm-up (start at 50%, then 70%, 85%, 92%, 96%, attempt max), never skip the warm-up, always have a spotter for bench press and squats, don't test 1RM when fatigued or after high-volume training. Most coaches recommend testing 1RM no more than 3–4 times per year.
Each formula was derived from different populations (powerlifters, untrained subjects, athletes) and assumes different rep-strength relationships. Formulas that use exponential decay (Mayhew, Wathan) tend to be more accurate at higher rep ranges. Simple formulas (Epley, Brzycki) are more accurate at 1–5 reps. Using the average minimizes individual formula biases.