Productive ToolboxOne Rep Max Calculator
Estimate your one-rep max from any set of reps with seven formulas, and get training weights from 50% to 95% of your 1RM.
Most accurate at 2–10 reps
| Formula | Estimated 1RM |
|---|---|
| Epley | 116.7 kg |
| Brzycki | 112.5 kg |
| Lander | 113.7 kg |
| Lombardi | 117.5 kg |
| Mayhew | 119 kg |
| O'Conner | 112.5 kg |
| Wathan | 116.6 kg |
Estimated one-rep max
115.5 kg
Average of seven formulas
| % of 1RM | Weight | Loadable | ≈ Reps |
|---|---|---|---|
| 100% | 115.5 kg | 115 kg | 1 |
| 95% | 109.7 kg | 110 kg | 2 |
| 90% | 103.9 kg | 105 kg | 3 |
| 85% | 98.2 kg | 97.5 kg | 5 |
| 80% | 92.4 kg | 92.5 kg | 8 |
| 75% | 86.6 kg | 87.5 kg | 10 |
| 70% | 80.8 kg | 80 kg | 13 |
| 65% | 75.1 kg | 75 kg | 16 |
| 60% | 69.3 kg | 70 kg | 20 |
| 55% | 63.5 kg | 62.5 kg | 25 |
| 50% | 57.7 kg | 57.5 kg | 30 |
Next step
Related tools
The One-Rep Max Formulas
Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Rather than testing it directly, you can estimate it from a harder set of several reps; each formula below was fitted to data from lifters and gives slightly different results.
Epley = w × (1 + r ÷ 30)
Brzycki = w × 36 ÷ (37 − r)
Lander = 100 × w ÷ (101.3 − 2.67123 × r)
Lombardi = w × r0.10
Mayhew = 100 × w ÷ (52.2 + 41.9 × e−0.055r)
O'Conner = w × (1 + 0.025 × r)
Wathan = 100 × w ÷ (48.8 + 53.8 × e−0.075r)
w is the weight lifted and r the number of reps. Example: 225 lb for 5 reps gives an estimated 1RM of about 260 lb (Epley 262.5 lb, Brzycki 253.1 lb).
Percentage of 1RM and Typical Reps
| % of 1RM | Reps | Typical use |
|---|---|---|
| 95% | 2 | Maximal strength |
| 90% | 3–4 | Strength |
| 85% | 5–6 | Strength |
| 80% | 7–8 | Strength and size |
| 75% | 9–10 | Muscle growth |
| 70% | 11–12 | Muscle growth |
| 65% | 14–16 | Endurance, technique |
| 60% | 17–20 | Warm-up, technique |
Approximate; the reps you can manage at a given percentage vary with the lift and the lifter.
How to Use the One Rep Max Calculator
- 1Choose kg or lb: Pick the unit your weights are in.
- 2Enter your set: Type the weight you lifted and how many clean reps you completed; sets of 2 to 10 reps give the most reliable estimate.
- 3Read your 1RM: See the average estimate and the result from each of the seven formulas.
- 4Plan your training: Use the percentage chart for training loads from 50% to 95% of your 1RM, rounded to loadable weights, with the reps you can expect at each.
Frequently Asked Questions
How is a one-rep max estimated?
From a set taken close to failure, using formulas fitted to strength data. The Epley formula is 1RM = weight × (1 + reps ÷ 30) and the Brzycki formula is 1RM = weight × 36 ÷ (37 − reps). For 100 kg lifted for 5 reps, they give 116.7 kg and 112.5 kg; the average of all seven formulas here is about 115.5 kg.
Which 1RM formula is most accurate?
None is best for everyone. Brzycki tends to be closer at low reps and Epley at slightly higher reps, and results depend on the lift and your training. Averaging several formulas smooths out their differences.
How many reps should I use?
Between about 2 and 10. Above 10–12 reps, endurance plays a bigger part and the formulas diverge; a set of 3 to 5 heavy reps gives the closest estimate of a true single.
Is it safer to estimate than to test a 1RM?
Usually, yes. Testing a true maximum needs a proper warm-up, good technique and a spotter or safety bars, and carries a higher injury risk, especially for beginners. Estimating from a submaximal set lets you track strength without maxing out.
How do I use percentages of 1RM in training?
Strength work is often done at 80–90% of 1RM for 3–6 reps, muscle-building at 65–80% for 6–12 reps, and technique or speed work below 65%. The chart rounds each load to 2.5 kg or 5 lb so you can load the bar.
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