One Rep Max Calculator
Estimate your one-rep max from a weight and rep count, with common training percentages.
- Estimated one-rep max (kg)116.7
- 90% — heavy strength work (kg)105.0
- 80% — 5-rep range (kg)93.3
- 70% — volume work (kg)81.7
Inputs used
- Weight lifted100 kg
- Reps completed5
About this calculator
Your one-rep max (1RM) is the heaviest weight you could lift once with good form. Rather than testing it directly — which is demanding and risky without spotters — the Epley formula estimates it from any hard set: 1RM ≈ weight × (1 + reps ÷ 30).
The estimate is most accurate from low-rep sets; beyond about 10–12 reps the formulas drift, so use a heavy set of 3–6 for the best number. The percentages shown are the standard programming zones: around 90% for strength work in low reps, 80% for the classic 5-rep range, and 70% for volume work.
Estimated maxes are for planning loads, not for ego-testing them — work up gradually when attempting anything near the calculated number.
Quick reference
Estimated one-rep max by weight and reps
Epley-formula 1RM (kg) from the weight lifted and the reps completed in one set. The estimate is most reliable at low rep counts.
| Weight lifted | 1 | 2 | 3 | 5 | 8 | 10 |
|---|---|---|---|---|---|---|
| 40 kg | 41.3 | 42.7 | 44.0 | 46.7 | 50.7 | 53.3 |
| 50 kg | 51.7 | 53.3 | 55.0 | 58.3 | 63.3 | 66.7 |
| 60 kg | 62.0 | 64.0 | 66.0 | 70.0 | 76.0 | 80.0 |
| 70 kg | 72.3 | 74.7 | 77.0 | 81.7 | 88.7 | 93.3 |
| 80 kg | 82.7 | 85.3 | 88.0 | 93.3 | 101.3 | 106.7 |
| 90 kg | 93.0 | 96.0 | 99.0 | 105.0 | 114.0 | 120.0 |
| 100 kg | 103.3 | 106.7 | 110.0 | 116.7 | 126.7 | 133.3 |
| 110 kg | 113.7 | 117.3 | 121.0 | 128.3 | 139.3 | 146.7 |
| 120 kg | 124.0 | 128.0 | 132.0 | 140.0 | 152.0 | 160.0 |
| 140 kg | 144.7 | 149.3 | 154.0 | 163.3 | 177.3 | 186.7 |
Frequently asked questions
How is a one-rep max estimated?
This calculator uses the Epley formula: 1RM ≈ weight × (1 + reps ÷ 30). Lifting 100 kg for 5 reps estimates a one-rep max of about 116.7 kg, so a single hard set can stand in for a true max attempt.
How many reps give the most accurate estimate?
A heavy set of about 3–6 reps works best; beyond roughly 10–12 reps the formula tends to overestimate. Fewer reps at a heavier load stay closer to the real maximum because the equation was fitted to low-rep sets.
What do the training percentages mean?
They are common programming zones off your 1RM: about 90% for low-rep strength work, 80% for the classic 5-rep range and 70% for higher-volume sets. From a 116.7 kg estimate those come to roughly 105, 93 and 82 kg.
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Results are informational only — not financial, medical or legal advice.