Estimate your one-repetition maximum (1RM) using 7 different formulas. Enter the weight you lifted and the number of reps completed to see your estimated max.
For best accuracy, use a weight you can lift for 1–10 reps. Results become less reliable above 10 reps.
| Formula | Estimated 1RM (lb) |
|---|---|
| Epley | 262.5 |
| Brzycki | 253.1 |
| Lander | 255.8 |
| Lombardi | 264.3 |
| Mayhew | 267.8 |
| O'Conner | 253.1 |
| Wathan | 262.3 |
| Average | 260 lb |
Based on your estimated 1RM of 260 lb. Use these percentages to plan your training loads.
| % of 1RM | Weight (lb) | Rep Range | Goal |
|---|---|---|---|
| 100% | 260 | 1–2 | Max strength |
| 95% | 247 | 1–2 | Max strength |
| 90% | 234 | 3 | Max strength |
| 85% | 221 | 4–5 | Strength |
| 80% | 208 | 6 | Strength |
| 75% | 195 | 8 | Hypertrophy |
| 70% | 182 | 10 | Hypertrophy |
| 65% | 169 | 12 | Endurance |
| 60% | 156 | 15 | Endurance |
| 55% | 143 | 18 | Warm-up / active recovery |
| 50% | 130 | 20+ | Warm-up / active recovery |
You have just pulled 100 kg for six clean reps on the squat, next week's program calls for sets at 80%, and you have no intention of testing a true max on a tired Thursday. An estimate is the practical answer. This page runs your weight and rep count through seven published prediction formulas, averages them, and builds a percentage table you can load onto the bar.
Worked example: 100 kg for 6 reps. Epley gives 120.0 kg, Brzycki 116.1, Lander 117.3, Lombardi 119.6, Mayhew 121.5, O'Conner 115.0 and Wathan 120.3. The seven values add to 829.8, and the page averages them to 118.54, shown as 119 kg. Eighty percent of that is 0.80 × 119 = 95.2, shown as 95 kg in the table.
Where each number comes from, with w the weight lifted and r the reps. Epley = w × (1 + r ÷ 30) = 100 × 1.2 = 120. Brzycki = w × 36 ÷ (37 − r) = 100 × 36 ÷ 31 = 116.1. Lander = 100w ÷ (101.3 − 2.67123r) = 10,000 ÷ 85.27 = 117.3. Lombardi = w × r^0.10 = 100 × 1.196 = 119.6. O'Conner = w × (1 + 0.025r) = 115. Mayhew and Wathan use exponentials: Mayhew = 100w ÷ (52.2 + 41.9 × e^(−0.055r)) and Wathan = 100w ÷ (48.8 + 53.8 × e^(−0.075r)).
Rounding and limits: each formula is rounded to one decimal before averaging, and the average is then rounded to a whole number. Reps are clamped to between 1 and 20, and at exactly one rep every formula simply returns the weight lifted. The table multiplies the average by 100% down to 50% in steps of five and rounds to whole numbers. The rep-range and goal columns are fixed look-ups by percentage, for example 80% is listed as 6 reps, not something calculated from your own set.
At 6 reps with 100 kg, estimates run from 115 to 121.5 kg. At 12 reps they run from 128.2 (Lombardi) to 144.4 (Lander), a 16 kg spread. Each formula was fitted to a different group of lifters, and the fits drift apart as the set gets longer, so sets of five or fewer give the tightest answer.
No. Accuracy varies by lift and by person, and small-muscle isolation work can fatigue differently from a squat or bench press. Treat the figure as a planning number, and do not attempt a true one-rep max without a spotter or safety arms.
Enter whatever you moved and stay consistent. For a barbell that means the bar plus plates, 45 lb or 20 kg for a standard bar. For dumbbells, enter one dumbbell and read the answer as per hand.
The page clamps reps into the range 1 to 20. Zero becomes 1 and then returns your lifted weight as the max, and 30 is treated as 20, so neither is a trustworthy estimate.
The page uses one generic scale, such as 85% for 4 to 5 reps and 70% for 10. How many reps you can really do at a given percentage depends on the lift, your training history and fatigue, so your coach's numbers for you should win.