One Rep Max (1RM) Calculator
Estimate your maximal single-repetition lift capacity and generate an evidence-based percentage training table using validated biomechanical formulas.
One Rep Max (1RM) Calculator
Estimate maximal single-repetition strength and generate a complete percentage-based training table using Epley, Brzycki, and Lander equations.
Ensemble average of formulas
W × (1 + r / 30)
W / (1.0278 - 0.0278 × r)
(100 × W) / (101.3 - 2.67 × r)
| % of 1RM | Training Weight (kg) | Estimated Reps | Primary Training Focus |
|---|---|---|---|
| 100% | 115.1 kg | 1 reps | Maximal Strength / Peaking |
| 95% | 109.3 kg | 2 reps | Maximal Strength / Peaking |
| 90% | 103.6 kg | 3-4 reps | Maximal Strength / Peaking |
| 85% | 97.8 kg | 5-6 reps | Hypertrophy / Power |
| 80% | 92.1 kg | 7-8 reps | Hypertrophy / Power |
| 75% | 86.3 kg | 9-10 reps | Hypertrophy / Volume |
| 70% | 80.6 kg | 11-12 reps | Hypertrophy / Volume |
| 65% | 74.8 kg | 12+ reps | Muscular Endurance |
| 60% | 69.1 kg | 12+ reps | Muscular Endurance |
| 50% | 57.6 kg | 12+ reps | Muscular Endurance |
Clinical Screening Reference & Medical Notice
Calculations provided on HOW WEIGHT are based on published statistical standards (such as WHO, CDC, and peer-reviewed metabolic equations) and are intended for educational and general screening purposes only.
They do not directly measure body fat distribution or visceral adipose tissue, nor do they replace personalized clinical diagnostic evaluation by a licensed healthcare provider. Learn more about our clinical methodology & disclaimers →
Biomechanical Models for Submaximal Strength Estimation
Directly attempting a true one-repetition maximum lift introduces substantial acute injury risk to connective tissues and induces high systemic fatigue. To solve this, sports scientists developed mathematical regression models predicting 1RM from submaximal repetitions to failure. The relationship between percentage of 1RM and repetitions follows an inverse linear-log curve for low repetitions (1 to 10 reps), allowing athletes to program progressive overload with precision.
Epley Formula (1985)
Developed by Boyd Epley at the University of Nebraska. The most widely cited strength equation in powerlifting and American football strength conditioning.
Brzycki Formula (1993)
Authored by Matt Brzycki of Princeton University. Widely utilized in academic exercise physiology and collegiate sports testing protocols.
Lander Formula (1985)
Empirically validated across multi-joint compound barbell lifts with excellent stability in the 4-to-8 repetition testing range.
Worked 1RM Calculation Example
Suppose an athlete bench presses 100 kg (220.5 lbs) for 5 repetitions to technical failure:
- Epley calculation: 100 × (1 + 5 / 30) = 100 × 1.1667 = 116.7 kg.
- Brzycki calculation: 100 ÷ (1.0278 - 0.0278 × 5) = 100 ÷ 0.8888 = 112.5 kg.
- Lander calculation: (100 × 100) ÷ (101.3 - 2.671 × 5) = 10,000 ÷ 87.94 = 113.7 kg.
- Ensemble Average 1RM: ≈ 114.3 kg (252.0 lbs).
- Prescribed 80% Hypertrophy Set: 114.3 × 0.80 = 91.4 kg for 8 repetitions.
Frequently Asked Questions
What is a One Rep Max (1RM)?
Your One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition through a full range of motion with proper biomechanical technique. It serves as the baseline standard for prescribing resistance training intensities.
Which 1RM formula is the most accurate: Epley or Brzycki?
Both formulas are highly accurate when repetitions to fatigue are between 2 and 8 reps. The Epley formula (W × [1 + r / 30]) is slightly better validated for free weight squats and deadlifts. The Brzycki formula (W / [1.0278 - 0.0278 × r]) is often favored for bench presses. Above 10 reps, all submaximal prediction equations lose precision.
Why is testing submaximal reps safer than testing an actual true 1RM?
Testing a true maximal 1RM imposes peak mechanical stress on tendons, ligaments, and the central nervous system, significantly increasing the risk of acute musculoskeletal injury or form breakdown. Calculating 1RM from a controlled 3-to-5 rep set provides an equivalent estimation with vastly superior safety.
How do I use the percentage training table in my workouts?
Strength coaches organize training cycles around percentages of 1RM: 85–100% 1RM (1–5 reps) targets maximal neuromuscular recruitment and strength; 70–85% 1RM (6–12 reps) optimizes mechanical tension for muscular hypertrophy; and 50–65% 1RM (15+ reps) develops muscular endurance and explosive velocity.
How often should I recalculate my 1RM?
Intermediate and advanced lifters generally re-estimate their 1RM at the conclusion of a 4-to-8 week training block or mesocycle. Beginners experiencing rapid neuromuscular adaptation can update targets every 2 to 4 weeks.