BMI and Calorie Calculator
BMI, basal metabolic rate and daily energy needs, with the assumptions stated plainly.
Runs in your browserInput
Activity level
Result
BMI
22.5
Normal range
Basal metabolic rate
1568
kcal per day
Daily energy needs
2430
kcal per day
Weight at BMI 18.5 to 24.9
53.5 kg
– 72.0 kg
BMI bands used here are the WHO adult cut-offs: under 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight, 30 and above obese.
Good to know
- This is a calculator, not medical advice. Decisions about diet, weight or training belong with a doctor or a registered dietitian.
- Mifflin-St Jeor has typical errors around ten per cent, and the activity multiplier is the largest single source of error because people consistently overestimate how active they are.
- BMI only uses height and weight, so it cannot tell muscle from fat. It is a population screening tool and thresholds differ between countries and ethnic groups.
About this tool
Work out your body mass index, your basal metabolic rate and the calories you burn in a day at your activity level. Both metric and imperial units are supported, and results are shown in whichever system you entered, so you never have to convert in your head. The formulas and their limitations are written out on the page: an estimate based on height, weight, age and sex cannot see body composition, and it is not medical advice.
How to use it
- 1Choose metric or imperial, then enter your height, weight, age and sex.
- 2Pick the activity level that matches an average week rather than your best week.
- 3Read your BMI category, basal metabolic rate and estimated daily energy needs.
Frequently asked questions
Why does BMI call a muscular athlete overweight?
Because BMI only knows height and weight. Muscle is denser than fat, so a trained person with low body fat can sit in the overweight band without carrying excess fat. BMI is useful for looking at populations and for spotting trends in one person over time; for an individual it is a rough screen, not a diagnosis.
How accurate is the calorie estimate?
The Mifflin-St Jeor equation is the most accurate of the widely used formulas, with typical errors around ten per cent, and individual variation can be larger than that. Treat the number as a starting point, then adjust based on what actually happens to your weight over a few weeks. Activity multipliers are the biggest source of error, because self-reported activity levels are consistently overestimated.
Should I use this to decide how much to eat?
No. It is a calculator, not medical advice. Calorie needs change with medical conditions, medication, pregnancy, age and training load, and eating decisions belong with a doctor or a registered dietitian. The same applies to the BMI categories, which were designed for population screening and vary in their thresholds between countries and ethnic groups.