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.
Results are informational only — not financial, medical or legal advice.