One Rep Max Calculator
Calculate 1-Repetition Maximum (1RM) strength and training percentages across 7 formulas.
Input Parameters
Live Result
Details
Steps
Apply standard Epley Formula: Weight × (1 + Reps ÷ 30)
Cross-reference with Brzycki Formula: Weight × (36 ÷ (37 - Reps))
Calculate training intensity percentage breakdown
Quick Answer & Understanding Your Result
Your One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition with proper technique on compound lifts like bench press, squat, and deadlift.
The 3 Most Validated Clinical 1RM Formulas
- Brzycki Formula (Most Accurate for 1–10 Reps): 1RM = Weight × rac{36}{37 - Reps}
- Epley Formula (Powerlifting Standard): 1RM = Weight × (1 + 0.0333 × Reps)
- Lombardi Formula: 1RM = Weight × Reps^{0.10}
Standard 1RM Training Percentage Guidelines (NSCA)
- Maximal Strength (1–5 reps): 85% to 100% of 1RM
- Muscle Hypertrophy (6–12 reps): 67% to 85% of 1RM
- Muscular Endurance (15+ reps): Less than 67% of 1RM
Enter the weight lifted and repetitions completed above to calculate your exact 1RM and percentage load breakdown.
Formula & Calculation Logic
Mathematical FormulaApplies submaximal repetition extrapolation models validated by the National Strength and Conditioning Association (NSCA).
Step-by-Step Guide
Select Exercise Type
Choose Bench Press, Squat, Deadlift, Overhead Press, or General Lift.
Enter Weight Lifted
Input the working weight used for your set (kg or lbs).
Enter Completed Repetitions
Input repetitions performed to technical failure (best accuracy: 2 to 10 reps).
Review 1RM and Load Matrix
View your estimated 1RM and percentage targets from 50% to 95%.
Worked Examples Table
| Example | Input Values | Calculated Result | Explanation |
|---|---|---|---|
| Bench Press: 80 kg for 6 reps | 80 × (36 / 31) = 92.9 kg estimated 1RM. | ||
| Squat: 100 kg for 5 reps | 100 × (36 / 32) = 112.5 kg estimated 1RM. |
Frequently Asked Questions
Evidence-Based Methodology & Authoritative References
National Strength and Conditioning Association (NSCA) - Basics of Strength and Conditioning
Brzycki M. Strength testing—predicting a one-rep max from reps-to-fatigue. JOPERD. 1993
Standard: WHO Adult BMI Diagnostic Standard
Formula: Brzycki: 1RM = Weight × [36 / (37 - Reps)]
Last Reviewed: August 21, 2026
Primary Source: National Strength and Conditioning Association (NSCA) - Basics of Strength and Conditioning
Reference Document: Brzycki M. Strength testing—predicting a one-rep max from reps-to-fatigue. JOPERD. 1993
Computation Privacy: 100% client-side 0ms computation, zero data retention
Calculated health, metabolic, and biometric metrics are for general fitness and educational reference only. They do not substitute for professional medical advice, clinical diagnosis, or personalized treatment plans.
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Calculated results are modeled based on standard scientific and mathematical formulas. Please verify with domain-specific technical documentation for specialized applications.