Bench Press 1RM (Brzycki)

How the Brzycki 1RM formula works

Brzycki (1993) works out your one-rep max from a set you stopped short of failure: 1RM = weight × 36 / (37 − reps). Within the 1–10 reps range the error stays under about 5%. Past 10 reps it drifts, since the relationship between reps and your true max stops being linear once fatigue sets in. Two other formulas come up a lot: Epley (1RM = w·(1 + reps/30)) and Lombardi (1RM = w·reps^0.10). For moderate rep counts they land within 2–3 kg of each other, with Epley reading a bit high on long sets and Brzycki a touch low.

Example: 80 kg × 5 reps → 80 × 36 / (37 − 5) = 2880 / 32 = 90 kg estimated 1RM.

Applications

Powerlifters use it to plan squat, bench and deadlift attempts. It also feeds the training max in 5/3/1 Wendler, sets up percentage-based hypertrophy work (say, 70% of 1RM × 8–12 reps), builds competition warm-up tables, and helps you spot a plateau before it costs you weeks.

FAQ

Is it safe to skip a real 1RM test? For most lifters it is. Estimating from a 3–8 rep set is safer and you can repeat it reliably. Save the actual max-out for trained athletes who have a spotter.

Why does accuracy drop above 10 reps? On a long set your cardio gives out before the muscle does, so the set ends early and the formula reads low against your real 1RM.

Bench vs squat vs deadlift? Most of the validation work for Brzycki was done on the bench press. The curve looks much the same for squat and deadlift, though Epley tends to fit a bit better when the reps climb.