Strength & 1RMScope: Athletes & Trained Individuals
One Rep Max Calculator
Calculate maximum single-repetition lift capacity across Epley, Brzycki, and Lander formulas
Input Parameters
Real-time calculation updates dynamically as you adjust inputs. Values remain strictly local on your device.
Estimated 1RM (Epley Standard)100% 1RM
116.7kg
Equivalent to ~257 lbs
Brzycki Formula
112.5kg
Lander Formula
113.7kg
5-Formula Average
115.9kg
| Percentage | Working Weight (kg) | Working Weight (lb) | Typical Rep Range |
|---|---|---|---|
| 100% | 116.7 kg | 257 lb | 1 rep (Max effort) |
| 95% | 110.9 kg | 244 lb | 2 reps (Heavy strength) |
| 90% | 105 kg | 231 lb | 3–4 reps (Strength focus) |
| 85% | 99.2 kg | 219 lb | 5–6 reps (Strength / Power) |
| 80% | 93.4 kg | 206 lb | 7–8 reps (Hypertrophy) |
| 75% | 87.5 kg | 193 lb | 9–10 reps (Hypertrophy) |
| 70% | 81.7 kg | 180 lb | 11–12 reps (Hypertrophy) |
| 65% | 75.9 kg | 167 lb | 13–15 reps (Muscular endurance) |
| 60% | 70 kg | 154 lb | 16–20 reps (Endurance / Speed) |
| 55% | 64.2 kg | 142 lb | Warm-up / Deload |
| 50% | 58.4 kg | 129 lb | Warm-up / Deload |
Clinical Responsibility Note: Estimated 1RM is a mathematical projection. Formulas lose precision as repetitions exceed 10–12 reps.
Mathematical Formula & Scientific Methodology
Formula: Epley & Brzycki 1RM Estimations
Epley: 1RM = Weight × (1 + Reps/30) | Brzycki: 1RM = Weight × [36 / (37 - Reps)]Applies linear and hyperbola strength-endurance regression equations validated across collegiate and elite lifters.
Model Assumptions
- Repetitions completed with strict biomechanical form to near-failure
Variables & Standard Units
| Symbol | Physiological Meaning | Unit |
|---|---|---|
| Weight | Resistance lifted to technical momentary failure | kg or lb |
| Reps | Completed repetitions with proper form (ideally 2–10 reps) | dimensionless |
Scientific Limitations
- High rep sets (15+ reps) are confounded by cardiovascular endurance and local muscle acid buffering capacity
Peer-Reviewed Scientific Citations
Poundage chart. Boyd Epley Workout (1985)
Epley B (1985) — University of Nebraska-Lincoln Strength Training Manual
Key Finding: 1RM = weight * (1 + reps / 30). Highly accurate for resistance exercises within 1 to 10 repetitions.
Frequently Asked Questions
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