Estimate the maximum weight you can lift for one repetition from a set you already completed. Enter the load, how many reps you made (1–10), and optionally the output unit and formula. The result includes a repetition chart and a percentage-of-1RM table you can use to plan training loads.
Formula
Three formulas estimate 1RM from weight lifted (W) and repetitions (r):
Epley: 1RM = W × (1 + r / 30)
Brzycki: 1RM = W × 36 / (37 − r)
Lombardi: 1RM = W × r^0.10
Epley and Brzycki return the same value at 10 reps. The repetition table inverts the chosen formula so each row is the load that would produce the same 1RM; the 1-rep row is always 100% of the estimate. The percentage table multiplies the 1RM by 100%…50% and truncates the inverted formula to a whole-rep count.
These numbers are estimates. A true 1RM test should only be attempted with solid technique, a spotter, and enough rest between attempts. When in doubt, train below the estimate.
Training intensity (rule of thumb)
| % of 1RM | Typical emphasis |
|---|---|
| 50–60% | Power / speed (low reps, short rests) |
| ~70% | Muscular endurance (higher reps) |
| 70–80% | Hypertrophy (about 7–12 reps) |
| 80–100% | Strength (1–3 reps, use a spotter) |
Examples
100 kg for 5 reps (Epley)
100 × (1 + 5 / 30) = 100 × 35 / 30 = 116.7 kg. At that 1RM, five reps is about 86% (100.0 kg), 10 reps about 75% (87.5 kg), and 85% of 1RM is 99.2 kg for an estimated 5 reps.
225 lb for 8 reps (Epley)
225 × (1 + 8 / 30) = 225 × 38 / 30 = 285.0 lb.
Same 100 kg × 5 set, result in pounds
116.7 kg converts at 1 lb = 0.45359237 kg to 257.2 lb. Brzycki on the same set is 112.5 kg; Lombardi is 117.5 kg.