Enter the weight you lifted and how many reps you completed — the Epley formula estimates your one-rep max, plus a reference table for other rep counts.
Weight to lift for other rep counts, based on your estimated 1RM above.
| Reps | Weight |
|---|
This calculator applies the Epley formula: one-rep max = weight × (1 + reps ÷ 30). Five reps at 185 lb gives an estimated 215.8 lb.
It is not the only published formula, and the others do not agree with it. Two common alternatives are Brzycki (weight × 36 ÷ (37 − reps)) and Lombardi (weight × reps0.10). Run all three on the same 185 lb lift and the picture is reassuring at low reps and alarming at high ones:
| Reps | Epley | Brzycki | Lombardi | Spread |
|---|---|---|---|---|
| 3 | 203.5 | 195.9 | 206.5 | 10.6 lb |
| 5 | 215.8 | 208.1 | 217.3 | 9.2 lb |
| 8 | 234.3 | 229.7 | 227.8 | 6.6 lb |
| 12 | 259.0 | 266.4 | 237.2 | 29.2 lb |
| 15 | 277.5 | 302.7 | 242.5 | 60.2 lb |
Under about 8 reps the formulas agree within roughly 10 lb; at 15 reps they disagree by 60. That is the practical rule this page exists to give you: estimate from a set of 3 to 6 reps. Beyond ten, what you are measuring stops being strength and starts being muscular endurance, and no formula converts reliably between the two.
A set taken to genuine failure also matters more than the formula chosen. Five reps you could have made six of is not a five-rep max, and the estimate inherits that error directly.
Almost nobody needs their true one-rep max. They need the percentages that hang off it, because that is how programmes prescribe load. From the 215.8 lb estimate above:
| % of 1RM | Weight | Roughly | Typically used for |
|---|---|---|---|
| 95% | 205 lb | 2–3 reps | Peak strength |
| 90% | 194 lb | 4 reps | Strength |
| 85% | 183 lb | 6 reps | Strength / size |
| 80% | 173 lb | 8 reps | Hypertrophy |
| 75% | 162 lb | 10 reps | Hypertrophy |
| 70% | 151 lb | 12 reps | Volume / technique |
Because the estimate carries error, so does every percentage derived from it. Treat a prescribed load as a starting point to be adjusted by how the set actually feels, not a number to be obeyed.
A true one-rep max attempt is the highest-risk thing most lifters do: maximal load, deteriorating technique, and a bar that has to be dealt with if the rep fails. The estimate exists precisely so that a moderate set can substitute for that.
If you do test, it needs competent spotters, a full warm-up ramp, and a lift you can bail from safely. For most people training for strength or size, a 3–5 rep estimate updated every few weeks tracks progress just as well and costs nothing.
This is a general training estimate, not medical or coaching advice. It says nothing about whether a load is safe for your joints, your technique or your training history.
A one-rep max (1RM) is the heaviest weight you could lift for a single complete repetition of an exercise. It's used as a reference point for programming training intensity, since many strength programs prescribe work sets as a percentage of 1RM (like 80% for 5 reps) rather than an absolute weight, letting the program scale automatically as a lifter gets stronger.
Reasonably accurate up to around 10 reps; accuracy declines as rep count climbs higher since the relationship between reps-to-failure and fatigue becomes less linear at high rep ranges. The Brzycki formula (1RM = weight × 36 ÷ (37 − reps)) is a common alternative that can differ slightly from Epley, especially at higher rep counts — for the worked example below, Brzycki gives roughly 208.1 versus Epley's 215.8, a reminder that any formula-based estimate has some built-in uncertainty.
Actual maximal-effort single-rep testing carries real injury risk, especially without a spotter, proper warm-up, or for lifters newer to a movement's technique. Most structured programs use an estimated 1RM from a comfortably submaximal set — like this calculator provides — rather than testing a true max directly on a regular basis.
Many strength programs prescribe work sets as a percentage of estimated 1RM — for example, 5 sets of 5 at 80% of 1RM — so lifters can scale intensity consistently as their strength changes over a training cycle, without needing to retest a true max repeatedly. See the reference table above for the equivalent weight at a few other common rep targets.
Worked example: lifting 185 lb for 5 reps: 1RM = 185 × (1 + 5 ÷ 30) = 185 × 1.1667 ≈ 215.8 lb. At that estimated 1RM, the weight for 3 reps would be about 196.2 lb, for 8 reps about 170.4 lb, and for 10 reps about 161.9 lb.
Training with a target heart rate in mind too? See the Target Heart Rate Calculator.