BMI & Calorie Calculator

This calculator gives you three answers from one short form. First your body mass index (BMI), shown on a coloured scale with the World Health Organization category it falls into. Second, the healthy weight range for your height, and roughly how much you would need to gain or lose to reach it. Third, how many calories your body uses at rest and across a normal day, with daily targets for losing, keeping or gaining weight.

You can type in centimetres and kilograms, feet and pounds, or feet with stone and pounds, and switch between them at any time without retyping. There is a switch for the lower BMI cut-offs the WHO suggests for people of Asian heritage, an optional waist measurement for a second check that BMI alone misses, and calories in kcal or kilojoules for anyone reading Australian food labels.

Everything is worked out by your browser, so your height, weight and age never leave your device and nothing is stored. It is written for adults. It says plainly where BMI falls short, for muscular people, older adults, pregnancy and anyone under 18, and it is a guide rather than medical advice.

1. Pick your units at the top: “cm · kg”, “ft · lb” or “ft · st”.
2. Type your height, weight and age, and choose Female or Male (the calorie formula differs slightly).
3. Choose how active you are from the list. Add your waist if you want the waist-to-height check.
4. Read your BMI, category and healthy weight range. Tick “Asian cut-offs” if they apply to you.
5. Check the “Daily calories” card for your goal, switch to kJ if you prefer, and tap “Copy results” to keep a note.

• BMI to one decimal place, with the WHO adult category from underweight to obese class III.
• A coloured BMI scale with a marker showing exactly where you sit.
• Healthy weight range for your height, plus how far you are from it, in your own units.
• Metric, US (feet, inches, pounds) and UK (stone and pounds) units, converted for you when you switch.
• Optional Asian cut-offs (23 and 27.5), following the WHO expert consultation.
• Resting energy (BMR) with the Mifflin–St Jeor formula and daily needs (TDEE) for five activity levels.
• Calorie targets to lose or gain about 0.25 or 0.5 kg a week, with a warning when a target drops too low.
• Waist-to-height ratio and BMI Prime as extra checks, and calories in kcal or kJ.

• Weigh yourself at the same time of day, ideally in the morning before eating. Your weight can swing by a kilo or two over a day without any real change.
• If you lift weights or play a lot of sport, BMI may call you overweight when you are not. A waist under half your height is a better sign that the extra weight is muscle.
• Calorie numbers are averages from a formula. Use them as a starting point for two or three weeks, then adjust by 100–200 kcal if your weight is not moving the way you expect.
• Slow and steady wins: about 0.25–0.5 kg a week is easier to keep off. The calculator flags any target below 1,200 kcal (women) or 1,500 kcal (men), which needs medical support.
• Activity levels are easy to overestimate. If you are unsure, pick the lower one.