Calorie Calculator
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Work out how many calories you burn a day, and what to eat for a goal.
- Enter your sex, age, height and weight, in metric or imperial
- Pick the activity level that matches your average week, not your best one
- Read your maintenance calories, then the target for the goal you want
To stay the same weight
This equation was fitted on adults. The figure above is unreliable for these numbers.
Your targets
- Lose 1 kg a week
- Lose 0.5 kg a week
- Maintain
- Gain 0.5 kg a week
- Gain 1 kg a week
The formula cannot see body composition, and the activity multiplier is the weakest part of it. Treat this as a starting point to adjust from, not a measurement.
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About this tool
This works out how many calories your body spends in a day, which is a different question from how many are in your lunch — nothing is looked up, and no food database is involved. It starts with your basal metabolic rate: what you would burn lying still for twenty-four hours, estimated from height, weight, age and sex using the Mifflin-St Jeor equation. Most calculators still use Harris-Benedict, which is fifty years older and runs about five percent high — a hundred calories a day, always in the direction of wondering why nothing is happening. That resting figure is then multiplied by how much you move, giving your total daily energy expenditure, and the goal targets are simply that number plus or minus a deficit. Two things are worth knowing before you trust the answer. The formula cannot see body composition, so a lean person and a heavier one of identical height, weight and age get the same estimate although muscle costs more to keep. And the activity multiplier is where the error really lives: the brackets are broad, most people place themselves a step too high, and the gap between two of them is several hundred calories. Treat the result as a starting point to adjust from, not a measurement.
Frequently asked questions
Does this need a food database?
No. It calculates what your body burns, not what food contains — those are two different tools that share a name. Everything here is arithmetic from your height, weight, age, sex and activity level, which is why it runs entirely in your browser with nothing sent anywhere.
Is this a TDEE calculator?
It is — TDEE means total daily energy expenditure, and it is the number this page exists to produce: everything you burn in a day, resting plus moving. The BMR calculator figure sits inside it as the resting part, which is the larger share and the one people are surprised by. Together they answer how many calories should i eat, for maintaining, losing or gaining.
What is BMR, and how is it different from TDEE?
BMR is your basal metabolic rate: the calories you would burn doing absolutely nothing for a day, which is most of your total. TDEE is that figure multiplied by how active you are, and it is the number that actually matters for eating — for most people it lands between 1.2 and 1.9 times their BMR.
Which formula does it use?
Mifflin-St Jeor, published in 1990. Harris-Benedict is more widely used and dates from 1919; it overestimates by roughly five percent for most people. Both estimate the same thing from the same four inputs, so the difference is not accuracy of measurement but which population the equation was fitted to.
How accurate is it?
The resting figure is the reliable part, typically within about ten percent for adults. The activity multiplier is not: the brackets are broad and self-assessment is generous, so the total can easily be out by two or three hundred calories. Use it as a starting point, then adjust by what actually happens over a few weeks.
Why will it not show me a lower target?
Targets below 1,200 calories for women and 1,500 for men are left blank rather than shown. Below that it becomes difficult to get enough vitamins and minerals from food at all. They are left blank rather than rounded up to that floor for a specific reason: if you burn 1,100 calories a day, printing 1,200 under “lose weight” would be a number above what you spend, and following it you would gain. A target that cannot be given safely is better absent than adjusted into something untrue.
Is it right for children, or during pregnancy?
No. The equation was fitted on adults, and a growing child's needs are driven by growth rather than by size alone. Pregnancy and breastfeeding both add requirements this does not model. In either case the number here is not the one to use.
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