One Rep Max Calculator
Estimate your maximum lift from any weight and rep count — with training percentage table
Lift Details
Weight Lifted (kg)
kg
Reps Completed
reps
Most accurate with 1–10 reps. Accuracy decreases above 15 reps.
Formulas Used
Epley: W × (1 + r/30)
Brzycki: W × 36/(37−r)
Lombardi: W × r^0.10
Mayhew: 100W / (52.2 + 41.9e^−0.055r)
Estimated 1RM (Average)
—
Use as a training reference, not for testing
Epley Formula—
Brzycki Formula—
Lombardi Formula—
Mayhew Formula—
Training Percentage Table
| % of 1RM | Weight | Rep Range |
|---|
What is One Rep Max (1RM)?
Your one rep max (1RM) is the maximum weight you can lift for a single repetition with proper form on a given exercise. It's the gold standard measure of absolute strength and is used to prescribe training loads as percentages — e.g., "do 4 sets at 80% of 1RM."
Actually attempting your true 1RM carries injury risk and requires significant warm-up. This calculator estimates your 1RM from a submaximal effort (e.g., the weight you can lift 5 times) using validated formulas — a safer approach for most training contexts.
lightbulb Training Application
Bench press: You complete 5 reps at 80 kg.
1Estimated 1RM ≈ 90 kg
2Strength work (85%): 76.5 kg × 3 reps
3Hypertrophy (75%): 67.5 kg × 8–12 reps
✓ Endurance (60%): 54 kg × 15+ reps
How to Use 1RM for Training
- Strength (90–97%): 1–3 reps — develops maximum neural strength, minimal hypertrophy
- Power (75–90%): 3–5 reps — combines strength and speed for athletic performance
- Hypertrophy (67–85%): 6–12 reps — optimal muscle growth stimulus for most people
- Muscular endurance (50–67%): 12–20+ reps — builds local muscular endurance and conditioning
- Warm up progressively before heavy sets — never jump straight to high percentages
- Re-test your 1RM estimate every 4–6 weeks as your strength progresses
Key Terms
- Rep Max (RM)
- The maximum weight you can lift for a given number of repetitions. 5RM = the heaviest weight you can lift 5 times. 10RM = for 10 reps, etc.
- RPE (Rate of Perceived Exertion)
- A 1–10 scale of effort. RPE 10 = maximum, couldn't do another rep. RPE 8 = 2 reps in reserve. Many modern strength programs use RPE rather than fixed percentages for better auto-regulation.
- Progressive Overload
- The principle that strength gains require progressively increasing the demand — more weight, more reps, or less rest over time. Tracking 1RM helps verify progressive overload is occurring.
quizFrequently Asked Questions
How accurate is the estimated 1RM from this calculator?
Accuracy varies by rep range and individual. With 1–5 reps, estimates are typically within 5% of actual 1RM. With 6–10 reps, error increases to 5–10%. Above 12–15 reps, accuracy drops significantly (10–20%+) because high-rep performance depends heavily on muscular endurance and cardiovascular fitness, not just strength. The most accurate estimate comes from using 3–5 rep sets at a challenging but not maximum effort. The calculator averages four formulas to reduce individual formula bias.
Should I actually test my 1RM?
Actual 1RM testing is appropriate for: competitive powerlifters (it's the sport), experienced lifters who need precise programming, and periodic testing (every 3–6 months) to track progress. For most recreational gym-goers, submaximal estimation is safer and practically equivalent. Actual 1RM testing requires: expert spotters, extensive warm-up (45–60 min), fresh and rested state, and practiced technique — maxing out on a fatigued or undertrained nervous system risks injury and underperformance anyway.
What are good 1RM benchmarks for beginners and intermediates?
Common strength standards as multiples of bodyweight (male / female): Bench press: Beginner 0.5×/0.35×, Intermediate 1.0×/0.65×, Advanced 1.5×/1.0×. Squat: Beginner 0.75×/0.5×, Intermediate 1.25×/0.85×, Advanced 2.0×/1.25×. Deadlift: Beginner 1.0×/0.65×, Intermediate 1.5×/1.0×, Advanced 2.5×/1.75×. Overhead press: Beginner 0.35×/0.2×, Intermediate 0.65×/0.4×, Advanced 1.0×/0.65×. These are global averages — Indian gym training norms are broadly similar.