Free Health & Fitness

Know your numbers: calorie/TDEE, BMR, body fat (U.S. Navy method), macro splitter, ideal weight range, running pace, one-rep max, heart-rate zones, sleep cycle timing, and a period tracker. Estimates are clearly labeled as estimates — these inform, they don't diagnose.

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Calorie / TDEE Calculator

Daily calories to lose, maintain, or gain weight.

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BMR Calculator

Your resting burn: basal metabolic rate, explained.

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Body Fat Calculator

U.S. Navy tape-method body fat % and category.

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Macro Splitter

Protein, carbs, and fat grams from your calorie target.

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Ideal Weight Range

Devine, Hamwi, Robinson, Miller + BMI range from your height.

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Running Pace Calculator

Pace, speed, finish times, and race predictions.

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One-Rep Max Calculator

Your 1RM from any lift, plus a training table.

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Heart Rate Zones

Your five training zones from age and resting HR.

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Sleep Cycle Calculator

Bedtimes and wake times on 90-minute cycles.

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Period Tracker

Predicted periods, ovulation, and fertile windows.

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Related categories

Calculators Everyday & Fun Study Tools

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Browse all categories

Every category on the codex, from study tools to ciphers — pick your starting point.

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Prompt Simulator

Practice prompt engineering: write prompts, get scored 0–10.

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GPA Calculator

Semester and cumulative GPA with weighted scales and a target planner.

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About these health & fitness

Every tool below is free, works in your browser, and needs no account.

How accurate are these calculators?
They use standard published formulas (Mifflin-St Jeor, Navy body-fat, etc.). They're good estimates for planning — not medical advice, and not a substitute for a professional.
Is my health data stored anywhere?
No. Everything is computed in your browser and nothing is sent or stored on any server.
What should my calorie target be?
The calorie calculator estimates your TDEE from your stats and activity, then suggests targets for maintaining, losing, or gaining — with a safety floor so targets never drop too low.