Calorie Calculator
How many calories you burn in a day, what to eat for your goal, and how to split it across protein, carbs and fat.
Result
What this calculator does
Your body burns calories doing nothing at all — keeping your heart beating, your brain running and your temperature steady. That floor is your basal metabolic rate. Add everything you do on top of it, from walking to the kitchen to a hard training session, and you get your total daily energy expenditure, or TDEE. That is the number that decides whether your weight moves.
This calculator estimates both, then adjusts for your goal and suggests a protein, carbohydrate and fat split to fit. Three published equations are available, because they disagree: Mifflin–St Jeor is the most reliable for most adults, Harris–Benedict is the older standard still used in clinical settings, and Katch–McArdle is the most accurate if you know your body-fat percentage.
How to use it
- Enter your sex, age, height and weight. Switch between metric and imperial at any point — your figures convert automatically.
- Pick the activity level that matches a typical week, not your best week. Most people overestimate this by one level.
- Choose your goal. The calculator applies a sensible calorie deficit or surplus rather than an aggressive one.
- Read your target calories and the macro split beneath. Use Copy to paste the whole summary into a notes app or send it to a coach.
The formula
Mifflin–St Jeor (default)
men BMR = 10w + 6.25h − 5a + 5
women BMR = 10w + 6.25h − 5a − 161
Harris–Benedict (revised 1984)
men BMR = 88.362 + 13.397w + 4.799h − 5.677a
women BMR = 447.593 + 9.247w + 3.098h − 4.330a
Katch–McArdle
BMR = 370 + 21.6 × lean body mass (kg)
TDEE = BMR × activity multiplier (1.2 to 1.9)
w is weight in kilograms, h is height in centimetres, a is age in years. Imperial entries are converted before the equation runs.
Worked examples
| Scenario | What you enter | Result |
|---|---|---|
| Man, 34, 175 cm, 72 kg, moderately active, maintaining | Mifflin | BMR 1,649 · TDEE 2,556 kcal |
| Woman, 29, 165 cm, 62 kg, lightly active, losing 0.5 kg/week | Mifflin | TDEE 1,850 · target 1,480 kcal |
| Man, 45, 180 cm, 95 kg, sedentary, losing slowly | Mifflin | TDEE 2,226 · target 2,003 kcal |
| Woman, 24, 170 cm, 58 kg, athlete, lean bulk | Mifflin | TDEE 2,587 · target 2,846 kcal |
| Man, 30, 178 cm, 80 kg, 15% body fat, moderate | Katch | BMR 1,839 · TDEE 2,850 kcal |
Frequently asked questions
BMR is what you would burn lying in bed all day — roughly 60 to 70% of your total for most people. TDEE is BMR multiplied by an activity factor to account for everything else you do, including digestion and fidgeting. TDEE is the figure that matters for eating: eat at it and weight holds steady, below it and you lose, above it and you gain.
Mifflin–St Jeor unless you have a reason not to. It was derived from a more modern population than Harris–Benedict and validation studies generally find it closer for the majority of adults. Use Katch–McArdle if you have a reliable body-fat measurement, since working from lean mass sidesteps the body-composition problem entirely. Harris–Benedict is included because many clinical references still quote it.
They are estimates, and they carry real spread. Even the best equations sit within about 10% of measured values for most people, which on a 2,500 kcal TDEE is a 250 kcal band. Treat the figure as a starting point: eat at it for two or three weeks, track your weight, and adjust by 100–200 kcal based on what actually happens on the scale.
Because it is a multiplier, so the error compounds. Moving from sedentary (×1.2) to very active (×1.725) raises a 1,700 kcal BMR by more than 900 kcal a day. Most people classify themselves one level too high, counting an intention to train rather than a habit. If you are unsure, pick the lower option — being pleasantly surprised beats a stalled diet.
It is the traditional rule of thumb for about half a kilo a week, based on the idea that a kilo of fat holds roughly 7,700 calories. It works reasonably well at first, but the body adapts: metabolic rate falls a little as you get lighter and move less. Recalculate every four to six kilos rather than holding one number all the way down.
They follow mainstream sports-nutrition practice. Protein rises when you are in a deficit because it preserves muscle and keeps you full; carbohydrate rises when you are building because it fuels training. Fat stays around a quarter to a third of intake, which is enough for hormone production. These are reasonable defaults, not prescriptions — plenty of people do well on different splits.
Going very low without supervision is a bad idea. Most guidance puts the floor at roughly 1,500 kcal a day for men and 1,200 for women; below that it is hard to get enough protein, vitamins and minerals, and muscle loss accelerates. Very-low-calorie diets do exist, but they belong under medical supervision, not a web calculator.
No. Thyroid conditions, diabetes, some medications, pregnancy and breastfeeding all change energy needs in ways no general equation captures. If any of those apply to you, use this only as background reading and get your numbers from a doctor or a registered dietitian who knows your history.
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