One-Rep Max (1RM) Calculator
Predict your maximal single-rep strength, workout load percentages, and progressive warm-up sets safely from submaximal reps.
Calculated from 100 kg × 5 reps. Your 5RM is approximately 87% of your theoretical 1RM.
1RM Percentage & Repetition Range Matrix
Full training percentage breakdown based on your calculated 1RM:
| Percentage of 1RM | Target Weight Load | Max Rep Capacity | Primary Training Adaptation |
|---|---|---|---|
| 100% 1RM | 114.8 kg | 1 Rep | Peak neural output & competitive 1RM test |
| 95% 1RM | 109.1 kg | 2 Reps | Maximal strength & high-threshold motor unit recruitment |
| 90% 1RM | 103.3 kg | 3–4 Reps | Heavy strength triples & CNS potentiation |
| 85% 1RM | 97.6 kg | 5–6 Reps | Gold standard strength hypertrophy overlap (5×5 routines) |
| 80% 1RM | 91.8 kg | 7–8 Reps | Muscle hypertrophy with significant mechanical tension |
| 75% 1RM | 86.1 kg | 9–10 Reps | Optimum volume threshold for muscle cross-sectional area |
| 70% 1RM | 80.4 kg | 11–12 Reps | Metabolic stress, sarcoplasmic hypertrophy & glycogen depletion |
| 60% 1RM | 68.9 kg | 15–20 Reps | Muscular endurance, dynamic effort speed work, or de-load |
Frequently Asked Questions
How accurate is a calculated One-Rep Max (1RM)?
Submaximal 1RM equations (Brzycki 1993, Epley 1985) are most accurate when tested with 2 to 10 repetitions to near-failure. When reps exceed 10–12, fatigue mechanisms shift toward muscular endurance, slightly reducing 1RM prediction precision.
What is the difference between the Brzycki and Epley formulas?
The Brzycki equation uses a linear fatigue slope and is exceptionally accurate for 3–8 reps in upper body presses. The Epley equation uses a slightly higher load coefficient and is widely favored in powerlifting and lower body compound movements (Squat and Deadlift).
Why should I calculate 1RM instead of testing a true 1RM maximum?
Testing a true 1RM maximum places maximal strain on ligaments, tendons, and the central nervous system (CNS), carrying elevated injury risk. Predicting 1RM from submaximal sets allows lifters to calculate precise training percentages safely and track progressive overload.
What percentage of 1RM should I use for muscle hypertrophy vs strength?
According to sports science literature (Schoenfeld et al.): For pure maximal strength and neural drive, use 85–100% 1RM (1–5 reps). For muscle hypertrophy, use 65–85% 1RM (6–12 reps). For muscular endurance, use 50–65% 1RM (15+ reps).
Scientific References
- Brzycki M. (1993). Strength testing—predicting a one-rep max from reps-to-fatigue. Journal of Physical Education, Recreation & Dance, 64(1), 88–90.
- Epley B. (1985). Poundage chart. Lincoln, NE: Boyd Epley Workout.
- Lombardi VP. (1989). Beginning Weight Training. Dubuque, IA: Wm. C. Brown Publishers.
- O'Conner B, Simmons J, O'Shea P. (1989). Weight Training Today. St. Paul, MN: West Publishing.
