Health & Fitness
One Rep Max Calculator
Estimate your one-rep max using three proven formulas. Get training percentages to program your workouts effectively.
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Estimated One Rep Max
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Training Percentages
How is this calculated?
Formulas: Three established 1RM estimation methods.
Brzycki Formula (best for 1–10 reps):
1RM = Weight × 36 / (37 − Reps)
Epley Formula (best for 5–15 reps):
1RM = Weight × (1 + Reps / 30)
Lombardi Formula (conservative):
1RM = Weight × Reps^0.10
Average 1RM = (Brzycki + Epley + Lombardi) / 3
Training Percentages:
95% = ~2 reps | 90% = ~3-4 reps
85% = ~5-6 reps | 80% = ~7-8 reps
75% = ~10 reps | 70% = ~12+ repsCalculation history
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Medical Disclaimer: This calculator provides estimates for informational purposes only. Never attempt a true 1RM without proper warm-up, spotters, and experience. These formulas are estimates and individual results vary. Consult a qualified trainer for programming guidance.
FAQ
Frequently asked questions
What is a one-rep max (1RM)?
Your one-rep max is the maximum amount of weight you can lift for a single repetition with proper form. It's used to gauge overall strength, program training percentages, and track progress over time. Directly testing 1RM carries injury risk, so estimation formulas based on sub-maximal lifts are commonly used instead.
Which 1RM formula is most accurate?
No formula is perfect — accuracy decreases as rep count increases. The Brzycki formula is most accurate for 1–10 reps, Epley works well for moderate rep ranges (5–15), and Lombardi provides conservative estimates. For best results, use a weight you can lift for 3–5 reps with good form. Above 10 reps, all formulas become less reliable.
How should I use training percentages?
Common programming uses: 90–100% for maximal strength (1–3 reps), 80–90% for strength (3–5 reps), 70–80% for hypertrophy (6–12 reps), 60–70% for muscular endurance (12–20 reps). These are guidelines — individual variation exists. Auto-regulation (RPE/RIR) can complement percentage-based training.
How often should I test my 1RM?
Direct 1RM testing is stressful and should be limited to every 8–16 weeks (typically at the end of a training block). Estimated 1RM from regular training sets can be tracked more frequently. If your estimated 1RM from a 5-rep set is increasing, your actual max is likely increasing too.
Are these formulas accurate for all exercises?
These formulas were developed primarily for barbell compound movements (squat, bench, deadlift). They're less accurate for isolation exercises, machines, and movements with significant technique components (Olympic lifts). They also assume reps are performed to or near failure. If you stop well short of failure, the estimate will be too low.