Epley formula
e1RM = weight × (1 + reps / 30). Tends to read slightly high above 6 reps.
Estimate your one-rep max from any rep set with the Epley and Brzycki formulas. Used inside The Training Notes for adaptive load planning.
Estimate your one-rep max from any rep set up to 12 reps. The output is an estimated 1RM (e1RM) — useful for picking working weights without ever actually testing a true max.
Your one-rep max is the most weight you can lift for a single rep with good form. Most lifters never test it directly because the recovery cost is high and the risk isn't worth the data point. The Epley and Brzycki formulas estimate it from a heavier set you actually did — both have been around for decades and tend to fall within 5% of a measured 1RM for most lifters in the 3–6 rep range.
e1RM = weight × (1 + reps / 30). Tends to read slightly high above 6 reps.
e1RM = weight × 36 / (37 − reps). Tends to read slightly high below 4 reps.
A lifter back squats 315 pounds for a set of 5 repetitions.
Calculation. Using the Epley formula, the estimated 1RM is 315 * (1 + 5 / 30), which equals 367.5 pounds.
Takeaway. Set your next training block's loads based on a 365-pound max.
A lifter bench presses 185 pounds for a set of 8 repetitions.
Calculation. Using the Brzycki formula, the estimated 1RM is 185 / (1.0278 - 0.0278 * 8), which equals 229.7 pounds.
Takeaway. Use a 230-pound max to calculate your percentages for future workouts.
Fix. These formulas are most accurate in the 1–10 rep range. If you complete a set of 15, your true 1RM is likely higher than the number predicted.
For most lifters, the average of Epley and Brzycki beats either one alone. Epley reads slightly high at 8+ reps; Brzycki reads slightly high at 1–3 reps.
Almost never. An e1RM from a heavy set of 3–5 is enough to pick training loads. Only powerlifters and strength athletes who compete at 1RM truly need to test it.
Yes — these formulas were validated mostly on barbell compound lifts. They're less reliable on isolation lifts and machines.
Every 3–4 weeks, or after a deload. Daily fluctuations are noise, not signal.
Most periodization works in percentages of 1RM. Knowing your e1RM lets you pick weights for any rep target without guessing.