One rep max (1RM) calculator
Estimate your 1RM from any set and get a rep-max table for programming.
Estimated 1RM
116.7 kg
Epley formula
| Reps | Weight | % 1RM |
|---|---|---|
| 1 | 116.5 kg | 100% |
| 2 | 109.5 kg | 94% |
| 3 | 106 kg | 91% |
| 5 | 100 kg | 86% |
| 8 | 92 kg | 79% |
| 10 | 87.5 kg | 75% |
| 12 | 83.5 kg | 71% |
How this was calculated: Epley: 1RM = weight × (1 + reps ÷ 30). Most accurate from sets of 3–8 taken close to failure.
Estimates for healthy adults, not medical advice. If you are pregnant, have a medical condition or a history of disordered eating, speak to a qualified professional first.
Worked example
100kg for 5 reps gives an estimated 1RM of about 116.7kg (100 × (1 + 5/30)). A rough 8-rep weight would be about 92kg.
Common questions
- How accurate is an estimated 1RM?
- Estimates are most accurate from sets of 3–8 reps taken close to failure. Above about 12 reps they become unreliable, so this calculator caps the estimate there.
- Do I need to test a true 1RM?
- Not to build strength or muscle. Tracking your estimated 1RM over time shows progress without the fatigue and risk of maximal attempts.
- Why do different calculators give different answers?
- They use different formulas (Epley, Brzycki and others). Use one consistently so changes reflect real progress.
Track every estimated 1RM and PR automatically.
ShreddedAI starts from these numbers, then learns from what you actually log — and tells you why every time it changes something.
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