Estimating a Max Without Testing One
A true one rep max is the heaviest weight you can lift once with good form. Testing it is fatiguing, requires spotters and carries injury risk, so lifters estimate it from a submaximal set instead. All the standard formulas do the same thing: add a percentage for each repetition completed.
| Formula | Equation | Best for |
|---|---|---|
| Epley | w × (1 + reps/30) | The most common; slightly high at high reps |
| Brzycki | w × 36 / (37 − reps) | Accurate at 10 reps or fewer |
| Lombardi | w × reps0.10 | Conservative across the range |
| O'Conner | w × (1 + reps/40) | The most conservative of the four |
They agree closely at low reps and diverge as reps rise. At 3 reps the spread is typically 2–3%; at 12 reps it can exceed 10%, which is why estimates from long sets should be treated as rough.
One Rep Max Percentage Chart
For a 1RM of 260 lb (118 kg):
| Percent | Weight | Typical reps | Training purpose |
|---|---|---|---|
| 100% | 260 lb | 1 | Testing a true max |
| 95% | 247 lb | 2 | Peaking, competition prep |
| 90% | 234 lb | 4 | Maximal strength |
| 85% | 221 lb | 6 | Strength |
| 80% | 208 lb | 8 | Strength and size |
| 75% | 195 lb | 10 | Hypertrophy |
| 70% | 182 lb | 12 | Hypertrophy, volume |
| 65% | 169 lb | 15 | Endurance, technique |
The Estimate Is Lift-Specific
Rep capacity at a given percentage differs by exercise. Squats and deadlifts, which use large muscle groups and allow a longer grind, typically produce more reps at a given percentage than the bench press. Isolation exercises differ more still. Percentage tables were built largely from powerlifting data and translate poorly to accessory work.
Using It to Program
Most strength programmes prescribe percentages of 1RM: 5×5 at 80%, 3×3 at 90%, and so on. Two practical points. First, recalculate every four to six weeks — a stale max makes the whole programme either too easy or unachievable. Second, many coaches now prefer RPE or reps-in-reserve, which adjust automatically to how you feel on the day rather than assuming a fixed number is always correct.
Frequently Asked Questions
How accurate are these estimates?
Within about 5% when derived from sets of 5 or fewer reps by an experienced lifter. Accuracy falls with higher reps and with less training experience.
Should I test my actual one rep max?
Rarely for general training — the fatigue and risk are not repaid. Competitive lifters test in a controlled peak; everyone else is better served by estimating from heavy triples.
Why is my estimate different between exercises?
Because rep endurance varies by movement. Calculate a separate max for each main lift rather than applying one figure across the board.