Estimate the heaviest weight you can lift once.
Epley: 1RM = weight × (1 + reps ÷ 30). Lifting 80 kg for 5 reps gives an estimated 1RM of about 92.4 kg (average of seven formulas).
Your one-rep max (1RM) is the most weight you can lift for a single repetition with good form. Testing it directly is risky, so this calculator estimates it from a lighter set of up to 12 reps using seven published formulas — Epley, Brzycki, Lander, Lombardi, Mayhew, O'Conner and Wathan — and gives you the average plus a table of training percentages.
Estimates are most accurate with 2–10 reps. Use a spotter and warm up properly. Eat enough protein to support strength training — see the Protein Calculator; track energy with the Calories Burned Calculator and TDEE Calculator.
The calculator applies the standard published formulas step by step.
| Item | Value |
|---|---|
| 100% of 1RM | 92.4 kg (about 1 reps) |
| 95% of 1RM | 87.8 kg (about 2 reps) |
| 90% of 1RM | 83.2 kg (about 4 reps) |
| 85% of 1RM | 78.5 kg (about 6 reps) |
| 80% of 1RM | 73.9 kg (about 8 reps) |
| 75% of 1RM | 69.3 kg (about 10 reps) |
| 70% of 1RM | 64.7 kg (about 12 reps) |
| 65% of 1RM | 60.1 kg (about 16 reps) |
| 60% of 1RM | 55.4 kg (about 20 reps) |
| 50% of 1RM | 46.2 kg (about 30 reps) |
| Formula | Estimated 1RM (kg) |
|---|---|
| Epley | 93.3 |
| Brzycki | 90 |
| Lander | 91 |
| Lombardi | 94 |
| Mayhew | 95.2 |
| O'Conner | 90 |
| Wathan | 93.3 |
| Reps | Estimated 1RM |
|---|---|
| 5 reps | 92.4 kg |
| 3 reps | 87.4 kg |
| 8 reps | 99.8 kg |
| 10 reps | 104.8 kg |
| 1 rep | 80 kg |
The maximum weight you can lift for one repetition of an exercise with correct technique.
Epley and Brzycki are the most common. Accuracy falls above about 10 reps, so use a heavier set.
It is safer to estimate it from a lighter set. If you test directly, warm up, use a spotter and safety bars.
About 70–85% for strength (3–8 reps) and 60–75% for muscle growth (8–12 reps).
Yes — calculate it separately for each lift, such as squat, bench press and deadlift.
Every 4–8 weeks, or whenever your working weights change noticeably.
It uses the published formula: Epley: 1RM = w × (1 + r ÷ 30) Brzycki: 1RM = w × 36 ÷ (37 − r) The full method and a worked example are shown on this page.
No. The calculator gives general estimates for information and education. It cannot diagnose or treat anything, so please speak to a doctor or qualified professional about your own health.
Yes. Choose centimetres or feet and inches for height, and kilograms, pounds or stone for weight; the results are converted for you.
No. Everything is calculated in your browser and nothing you enter is uploaded or saved.
