BMI Tracker

BMI (Body Mass Index) is your weight in kilograms divided by your height in metres squared. A BMI of 18.5–24.9 is classified as healthy weight by the World Health Organization. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.

According to the WHO, a healthy BMI for adults is 18.5–24.9. This directly corresponds to your Healthy Weight Range card — the minimum and maximum body weights that fall within this band for your exact height.

BMI is a useful population-level screening tool but has well-known limitations. It can overestimate fatness in very muscular people and underestimate it in older adults who have lost muscle. The WHO recommends using BMI alongside waist circumference and body fat percentage for a fuller picture — which is exactly why this dashboard shows multiple metrics together.

The dashboard uses the Deurenberg formula (1991): BF% = (1.20 × BMI) + (0.23 × Age) − (10.8 × sex factor) − 5.4. It is a statistical estimate derived from BMI, age and sex — less precise than DEXA scanning or hydrostatic weighing, but a useful benchmark. Very muscular individuals will see an overestimate.

Per American Council on Exercise guidelines — Men: essential fat 2–5%, athletic 6–13%, fitness 14–17%, acceptable 18–24%, obese 25%+. Women: essential 10–13%, athletic 14–20%, fitness 21–24%, acceptable 25–31%, obese 32%+. These ranges are shown colour-coded on the Body Fat card above.

The Devine formula (1974) is used: 50 kg + 2.3 kg per inch over 5 feet for men, and 45.5 kg + 2.3 kg per inch for women. This formula originated in clinical medicine for drug dosing and ventilator settings. Treat it as a reference point, not a strict personal goal — healthy weight ranges vary by build and muscle mass.

TDEE (Total Daily Energy Expenditure) is the total calories your body burns per day, including activity. It's calculated by first finding your BMR (Basal Metabolic Rate) using the Mifflin-St Jeor equation, then multiplying by an activity factor ranging from 1.2 (sedentary) to 1.9 (very active). Eating at your TDEE maintains weight; 500 kcal below causes roughly 0.5 kg of fat loss per week.

A 500 kcal/day deficit below your TDEE leads to approximately 0.5 kg of fat loss per week — a rate considered safe and sustainable. Avoid going below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision, as this can cause muscle loss and nutritional deficiencies.

The European Food Safety Authority (EFSA) recommends around 2.0 L/day for women and 2.5 L/day for men from all sources including food. This dashboard estimates 35 ml per kg of body weight, scaled up by activity level. In hot climates or after intense exercise, increase this further.

The WHO sets a minimum of 0.8 g per kg of body weight for sedentary adults. Active individuals need 1.4–1.6 g/kg, and athletes training hard need up to 2.0 g/kg according to ISSN research guidelines. The dashboard adjusts your protein target automatically whenever you change your activity level.

Yes. Switch between Metric (cm / kg) and Imperial (in / lbs) using the toggle at the top of the input panel. All 7 metrics — BMI, healthy weight range, body fat, ideal weight, calories, hydration and protein — recalculate instantly and display results in your chosen unit.

No. All calculations run entirely in your browser using JavaScript. Your height, weight, age and other inputs are never transmitted to or stored on our servers. Your data never leaves your device. See our Privacy Policy for full details.