One-Rep Max Calculator

How it's calculated

We average two well-known formulas for a balanced estimate:

• Epley: 1RM = weight × (1 + reps ÷ 30)
• Brzycki: 1RM = weight × 36 ÷ (37 − reps)

Both are most accurate for sets of about 10 reps or fewer — the further you get from a true max, the rougher the estimate. Never test an actual 1RM without a proper warm-up and, ideally, a spotter.

Training with percentages

Once you know your 1RM, you can program sets as a percentage of it — a common approach for strength work:

• Strength: 85–95% for 1–5 reps
• Muscle: 67–80% for 8–12 reps
• Endurance: under 67% for 12+ reps

Not sure how to lay out those sets? See how to structure a workout and how long to rest between sets.

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