🏋️ 1RM Calculator

Weight Unit

Weight Lifted (kg)

Reps Performed (1–15)

Exercise

⚠️ Never attempt a true 1RM without an experienced spotter. Estimated 1RMs are most accurate for reps in the 2–6 range. Accuracy decreases above 10 reps.

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kg — Estimated 1RM (Epley Formula)

📊 Training Percentage Chart

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Reps	% of 1RM	Weight	Zone	Goal
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🏆 Strength Standards

Compare your estimated 1RM to population strength standards (bodyweight multiples). Select your exercise above.

Body Weight

Gender

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📐 1RM Formulas Explained

Epley Formula (Most Common)

1RM = w × (1 + r/30) w = weight lifted r = reps performed Example: 100 kg × 5 reps 1RM = 100 × (1 + 5/30) = 100 × 1.167 = 116.7 kg Best for: General use, most commonly referenced. Tends to slightly overestimate at high reps.

Brzycki Formula

1RM = w × (36 / (37 - r)) Example: 100 kg × 5 reps 1RM = 100 × (36 / (37 - 5)) = 100 × (36 / 32) = 112.5 kg Best for: Lower rep ranges (1–10). Slightly more conservative than Epley.

Lander Formula

1RM = (100 × w) / (101.3 - 2.67123 × r) Example: 100 kg × 5 reps 1RM = 10000 / (101.3 - 13.356) = 10000 / 87.944 = 113.7 kg

Other Formulas

Lombardi: 1RM = w × r^0.10 Mayhew: 1RM = (100 × w) / (52.2 + 41.9 × e^(-0.055 × r)) O'Conner: 1RM = w × (1 + 0.025 × r) Wathan: 1RM = (100 × w) / (48.8 + 53.8 × e^(-0.075 × r)) Best practice: Use the AVERAGE of all formulas for the most reliable estimate, especially when reps are in the 3-8 range.

Training Zones by % of 1RM

95–100%: Max Strength (1–2 reps) — true 1RM zone 90–95%: Strength (2–3 reps) 85–90%: Strength/Power (3–5 reps) 80–85%: Strength/Hypertrophy (5–6 reps) 70–80%: Hypertrophy (8–12 reps) ← MUSCLE GAIN 60–70%: Hypertrophy/Endurance (12–15 reps) 50–60%: Muscular Endurance (15–20 reps) Below 50%: Warm-up / technique work

❓ Frequently Asked Questions

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🏋️ One-Rep Max Calculator