One Rep Max Formulas Explained: Epley vs Brzycki (With Examples)

Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Programmes often set training loads as a percentage of it, but a true max test is tiring and risky. Formulas let you estimate it from a lighter set.

Epley formula

1RM = weight × (1 + reps ÷ 30). If you bench 80 kg for 8 reps: 80 × (1 + 8/30) = 80 × 1.267 = about 101 kg. Epley is the formula used in our 1RM calculator.

Brzycki formula

1RM = weight × 36 ÷ (37 − reps). The same set gives 80 × 36 ÷ 29 = about 99 kg. As you can see, the two agree within a couple of kilograms.

Which is more accurate?

Both lose accuracy above about 10 reps because fatigue, not maximal strength, limits the set. For the best estimate use a hard set of 3–8 reps taken close to failure with a spotter or safety bars.

Turning 1RM into training weights

• 90–100%: singles and doubles for peak strength.
• 80–90%: sets of 3–6 for strength.
• 65–80%: sets of 6–12 for muscle growth.
• 50–65%: technique, warm-ups and endurance.

For example, with a 100 kg squat 1RM, 75 kg for 8–10 reps is a good muscle-building load.

Common mistakes

Do not use a warm-up set, a set with grinding form, or different exercise variations from week to week. Use the same lift, same range of motion and same equipment so your numbers are comparable.

How often to update

Recalculate every 4–8 weeks. If you are new, strength rises quickly, so retest sooner. New to lifting? Start with our strength training for beginners plan. Fuel your training with enough protein using the protein calculator.