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All calculators

30 free fitness and health calculators, each backed by a real, published formula — not a guess. Browse by category below.

Body Composition & Weight

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BMI, body fat, ideal weight, lean body mass, waist-to-hip ratio, and healthy weight — measures of what your body is made of.

Energy & Nutrition

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Calorie, BMR, TDEE, macro, protein, and water intake calculators — how much fuel and hydration your body needs.

Performance & Training

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One-rep max, target heart rate, pace, and calories burned — numbers that guide how you train and move.

Pregnancy & Cycle

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Due date, conception, ovulation, and pregnancy weight gain calculators — timeline tools for fertility and pregnancy.

Clinical & Lifestyle

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Kidney function, body surface area, and blood alcohol — measures that come from a lab report or a clinical setting rather than a gym.