How 1RM is estimated
Your one rep max (1RM) is the heaviest weight you can lift once with good form. Instead of testing it directly, you can estimate it from a set taken close to failure. Three common formulas, with w = weight and r = reps:
Epley: 1RM = w × (1 + r ÷ 30)
Brzycki: 1RM = w × 36 ÷ (37 − r)
Lombardi: 1RM = w × r0.10
Estimate = average of the three
Brzycki: 1RM = w × 36 ÷ (37 − r)
Lombardi: 1RM = w × r0.10
Estimate = average of the three
For a single rep (r = 1), the weight lifted is the 1RM, so all three are set to w.
Worked example
You bench 225 lb for 5 reps.
- Epley: 225 × (1 + 5/30) = 262.5 lb
- Brzycki: 225 × 36 ÷ 32 = 253.1 lb
- Lombardi: 225 × 50.10 = 264.3 lb
- Average: (262.5 + 253.1 + 264.3) ÷ 3 = about 260 lb
A set at 80% of that (208 lb) is a typical heavy working weight.
Limitations
- Reps above 12. The formulas spread apart as reps rise. Estimates from sets of 3 to 10 reps taken close to failure are the most useful.
- Exercise and person. Studies find the formulas fit some lifts (like the bench press) better than others (like the deadlift), and they differ between people.
- Reps in reserve. If you stopped well short of failure, your real 1RM is higher than the estimate.
Sources
- Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. JOPERD. 1993;64(1):88–90
- LeSuer DA et al. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. J Strength Cond Res. 1997;11(4):211–213 compares Epley, Brzycki, Lombardi and others.
Epley's formula comes from Boyd Epley's Poundage Chart (1985) and Lombardi's from Beginning Weight Training (1989).