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.
Estimated 3RM
104 kg
Estimated 5RM
98 kg
Estimated 10RM
86 kg
Uses standard 1RM estimation formulas. Reviewed for accuracy. 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)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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