One Rep Max Calculator
Estimate your one-rep max for any lift using proven formulas.
1RM estimates are for training guidance only and do not guarantee a safe max attempt.
One rep max calculator
Use a hard set performed with consistent technique. Estimates are usually more reliable from 1–10 reps.
Estimated one-rep max
115
kgBased on 5 reps at 100 kg using Average estimate. Average of all four formulas.
Rep maxes reverse the selected formula, so the rep max for the reps you entered equals the weight you lifted.
Estimated 3RM
106 kg
Estimated 5RM
100 kg
Estimated 10RM
89 kg
Uses standard 1RM estimation formulas. Estimate only. Not a substitute for coaching, medical, or professional fitness advice.
Personalized interpretation
Your estimated 1RM is 115 kg based on 5 reps at 100 kg.
For heavy strength work, 80–90% of estimated 1RM is commonly used. For technique or volume work, 60–75% may be more appropriate.
Estimates become less reliable when calculated from very high-rep sets. Use a spotter, safety arms, and proper warm-up when training near maximal loads.
Training percentage table
95%
109 kg
Near-max singles
90%
103 kg
Heavy strength work
85%
98 kg
Strength-focused sets
80%
92 kg
Strength / hypertrophy sets
75%
86 kg
Moderate volume work
70%
80 kg
Volume or technique work
65%
75 kg
Speed or lighter volume
60%
69 kg
Warm-up or speed work
50%
57 kg
Light technique or warm-up
What one rep max means
One rep max formulas compared
Epley
117 kg
Formula estimate based on the reps entered.
Brzycki
113 kg
Formula estimate based on the reps entered.
Lombardi
117 kg
Formula estimate based on the reps entered.
O’Conner
113 kg
Formula estimate based on the reps entered.
How to use estimated 1RM safely
Rep ranges and estimate accuracy
1–5 reps
Usually provides stronger estimates of maximal strength.
6–10 reps
Can still be useful, but may be more affected by fatigue and endurance.
10+ reps
Less reliable for maximal strength because high-rep endurance matters more.
Common mistakes and safety notes
This calculator is for training estimates only. It does not assess injury risk, technique quality, or readiness to max out. If you feel pain, dizziness, or unusual symptoms while lifting, stop and seek appropriate professional guidance.
Formula explanation
Epley: 1RM = Weight × (1 + Reps ÷ 30)Brzycki: 1RM = Weight × 36 ÷ (37 − Reps)Lombardi: 1RM = Weight × Reps^0.10O’Conner: 1RM = Weight × (1 + 0.025 × Reps)A 1-rep set is used directly as your 1RM. Average is the mean of the formulas that apply at your rep count; this calculator does not use Brzycki above 10 reps, where it rises steeply. Estimated 3RM, 5RM and 10RM divide the 1RM by the selected formula's multiplier for that rep count.
Example: 100 kg × 5 reps
Epley estimate: 1RM = 100 × (1 + 5 ÷ 30) ≈ 116.7 kg.
Example: 185 lb × 8 reps
Epley estimate: 1RM = 185 × (1 + 8 ÷ 30) ≈ 234 lb.
Frequently Asked Questions
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Estimate only. This calculator is for general education and planning. It is not medical advice, and not medical, nutrition, fitness, diagnosis, treatment, or emergency advice. Personal factors can change results. Fitness and body composition estimates are simplified and may vary by measurement method, training status, age, sex, health history, and equipment accuracy. Speak with a qualified professional for personal guidance.
Related reading
Learn the formula, assumptions, examples, or context behind this tool.