Free health calculators that measure up
BMI, calories, body fat, pregnancy dates and training numbers: 21 calculators built on published formulas, with the source named on every page. Nothing leaves your browser unless you ask.
BMI + calorie quick check
- Maintenance calories
- 1,892 kcal/day
- Healthy weight for your height
- 111 lb–150 lb
- Gentle weight-loss target
- 1,392 kcal/day
Full detail: BMI calculator · calorie calculator. Your numbers carry over to every tool.
Explain my result
Sends only the numbers shown above (no name, no account) to an AI model through Vercel AI Gateway. It explains; it doesn’t diagnose.
Every calculator
Body
- BMIBMI, BMI Prime and the healthy weight range for your height.
- BMI Chart by HeightLook up the healthy weight band for any adult height.
- Body Fat PercentageBody fat % from a tape measure, US Navy method.
- Lean Body MassEverything that isn’t fat: muscle, bone, organs, water.
- Ideal WeightFour classic formulas and the healthy BMI range.
- Waist-to-Height RatioIs your waist less than half your height?
- Waist-to-Hip RatioWhere you carry weight, against WHO cut-offs.
- Body Surface AreaBSA in m², Mosteller formula.
Energy & food
- CalorieMaintenance calories plus targets to lose or gain weight.
- TDEEHow many calories you burn in a typical day.
- BMRCalories your body uses at complete rest.
- MacroTurn a calorie target into grams of protein, carbs and fat.
- Protein IntakeDaily protein grams for your weight and training.
- Water IntakeDaily water guideline plus a glass tracker.
Pregnancy
My numbers
Results you save with “Save to My numbers” appear here. They live only in this browser.
How VitalMetrics works
Formulas you can check. Each page names its equation and the paper or health body behind it: Mifflin-St Jeor for calories, the US Navy circumference method for body fat, ACOG’s 280-day rule for due dates, Tanaka’s formula for maximum heart rate. The full list is on Sources & methods.
Private by design. All the maths runs in your browser. We keep your inputs in local storage so every calculator starts from your numbers, and you can erase them on the privacy page.
Explained, not diagnosed. Interactive explainers show why each formula behaves the way it does, and the optional AI explainer puts your result into plain words. None of it replaces a doctor, midwife or dietitian, who can look at the whole picture.
Questions
Are these health calculators free?
Yes. Every calculator on VitalMetrics is free, needs no account, and runs in your browser.
Is my health data stored anywhere?
Your inputs stay on your device. We remember them in your browser’s local storage so you don’t have to retype them, and you can wipe them with one button on the privacy page. The optional “Explain my result” feature sends only the numbers on screen to an AI model when you click it.
How accurate are the results?
Each calculator uses a published formula, cited on its page and on our sources page. They estimate population averages, so an individual result can be off. Treat them as a starting point for a conversation with a clinician.
Can I calculate BMI and calories together?
Yes. The quick check on this page gives your BMI and maintenance calories from one set of inputs, and every calculator shares the same saved height, weight and age.