Estimated 1RM from Submaximal Reps

For beginners, general-fitness clients, and anyone for whom maximal loading is unwise (RM-Loading Caution (Hamstring Curl & Stiff-Leg Deadlift)), 1RM can be estimated from a set taken to (or near) failure at a submaximal load. Accuracy is best when reps are ≤10 (ideally 3–6); error grows as reps increase because endurance and fiber-type differences enter.

Common equations (weight = load lifted, reps = reps completed):

• Epley: 1RM = weight × (1 + reps/30) — most accurate ~6–10 reps.
• Brzycki: 1RM = weight / (1.0278 − 0.0278 × reps) — most accurate ~1–5 reps.
• Lombardi: 1RM = weight × reps^0.10.
• O'Conner: 1RM = weight × (1 + 0.025 × reps).

Worked example (Epley): 8 reps at 200 lb → 200 × (1 + 8/30) = 200 × 1.267 ≈ 253 lb estimated 1RM.

Best practice: use strict, full-ROM reps to true or near failure; pick one equation and stay consistent for re-tests; cross-check against the %1RM ↔ reps table (%1RM ↔ Repetitions Relationship Table). Estimates diverge from each other and from a true max by several percent, so treat them as a working number for load prescription, not a competition total.

• Use sets of ≤10 reps (best 3–6) to failure; fewer reps = more accurate.
• Epley: 1RM = weight × (1 + reps/30); Brzycki: weight / (1.0278 − 0.0278·reps).
• Lombardi: weight × reps^0.10; O'Conner: weight × (1 + 0.025·reps).
• Equations disagree by a few %; pick one and reuse it for tracking.