BMI Calculator
Calculate your body mass index from metric or imperial measurements, with category guidance.
- Metric and imperial input
- Instant BMI category
- Healthy range estimate
Practical Health Calculators
Five focused tools for quick planning. No account, no paywall, no hidden steps.
Calorie Needs Calculator
Estimate daily maintenance calories using the Mifflin-St Jeor equation and activity level.
- BMR and TDEE output
- Maintenance, cut, and bulk targets
- Clear assumptions shown
Macro Calculator
Convert a daily calorie target into grams of protein, carbs, and fats with preset ratios.
- Popular split presets
- Custom percentage mode
- Grams and calories side-by-side
Protein Calculator
Estimate daily protein grams using your body weight, training goal, and activity level.
- Goal-specific protein ranges
- Kilogram and pound support
- Daily and per-meal guidance
Water Intake Calculator
Estimate a daily hydration target from body weight, activity minutes, and climate conditions.
- Metric and imperial weight modes
- Activity and climate adjustments
- Liters, cups, and bottle guidance
Important note
These calculators are educational and not medical advice. If you have a condition, are pregnant, or have diet restrictions, consult a licensed clinician.
Health Calculator FAQ
Are these calculators free?
Yes, all HealthKit calculators are free and available without signup.
Which calculator should I start with?
Most users start with calories (TDEE), then protein and macros for intake targets, and BMI as a quick screening metric.
How does the hydration tool estimate water intake?
It uses a bodyweight baseline and adjusts for activity and hotter climates to generate a practical daily hydration target.
Can calculator results replace medical guidance?
No. These tools provide estimates and should be combined with advice from a licensed clinician when needed.
Related Tools
Improve recovery planning with SleepKit for bedtime and wake-time cycle planning. Turn that routine into an execution plan with FocusKit. Need date and budget planning too? Use DateKit and BudgetKit. Browse the full suite directory in Life Kits.