BMI and calorie calculator
See your body mass index with the WHO adult categories, and an estimate of the calories you need each day. For adults only. Not medical advice.
Sex, age and activity are used only for the calorie estimate, not for BMI.
Runs on your phone. Nothing is uploaded or saved.
What the numbers mean, and what they don't
BMI = weight in kg ÷ (height in m)². It does not measure body fat: a muscular person can score "overweight", and someone with a "normal" BMI can still carry a lot of fat around the waist. Waist size and a check-up tell you more.
The adult categories are not for children and teenagers (they use BMI-for-age charts), and not for pregnancy. They are also less accurate for older people and some athletes.
A WHO expert group found that many Asian populations face higher health risks at lower BMI, and suggested extra action points at 23 and 27.5. If that applies to you, ask your doctor which cut-offs to use.
Mifflin-St Jeor estimates the energy you burn at rest; the activity factor scales it up. Real needs can differ by a few hundred calories a day. A deficit of about 500 a day is the usual starting point for losing about 0.5 kg a week.
Not medical advice. This page gives general estimates only. Talk to a doctor before you change how you eat, especially if you are pregnant, under 18, over 65, have a health condition or take medicine.
Sources: World Health Organization, "Obesity and overweight" fact sheet (who.int; adult overweight is BMI ≥ 25 and obesity BMI ≥ 30; 45% of adults were overweight in 2024) and WHO BMI classification for adults (underweight below 18.5, normal 18.5–24.9, obesity classes I–III from 30, 35 and 40; WHO Technical Report Series 894, 2000); WHO Expert Consultation, "Appropriate body-mass index for Asian populations", The Lancet, 2004;363:157–63. Calories: Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO, "A new predictive equation for resting energy expenditure in healthy individuals", American Journal of Clinical Nutrition, 1990;51:241–247. Activity factors (1.2 to 1.9) are the multipliers commonly used with this equation. Deficit of about 500 kcal/day for about 0.5 kg/week: US National Heart, Lung, and Blood Institute, Clinical Guidelines on Overweight and Obesity in Adults, 1998. Not medical advice: talk to a doctor.