Calorie Intake Calculator
What the calorie intake calculator does
The calorie intake calculator estimates how many kilocalories you burn in a typical day, which is the amount you need to eat to keep your weight stable. Enter your weight in kilograms, height in centimetres, age and sex, choose an activity level, and press Calculate. The result is your total daily energy expenditure (TDEE).
The formula
The tool uses the Mifflin-St Jeor equation, which studies have found to be the most accurate of the common resting-metabolism formulas for adults:
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
BMR is the energy your body uses at complete rest. The calculator then multiplies it by an activity factor:
| Activity level | Multiplier | Describes |
|---|---|---|
| Sedentary | 1.2 | Desk job, little or no planned exercise |
| Lightly active | 1.375 | Light exercise 1 to 3 days a week |
| Moderately active | 1.55 | Moderate exercise 3 to 5 days a week |
| Very active | 1.725 | Hard exercise 6 to 7 days a week or a physical job |
Worked examples
A 35-year-old man, 80 kg, 178 cm, moderately active. BMR = 800 + 1112.5 − 175 + 5 = 1,742.5 kcal. TDEE = 1,742.5 × 1.55 = 2,701 kcal per day.
A 28-year-old woman, 62 kg, 165 cm, lightly active. BMR = 620 + 1031.25 − 140 − 161 = 1,350 kcal. TDEE = 1,350 × 1.375 = 1,857 kcal per day.
A 60-year-old man, 90 kg, 175 cm, sedentary. BMR = 900 + 1093.75 − 300 + 5 = 1,699 kcal. TDEE = 1,699 × 1.2 = 2,038 kcal per day.
Using the number for weight goals
| Goal | Daily intake | Expected change |
|---|---|---|
| Maintain weight | TDEE | Stable |
| Lose slowly | TDEE − 250 | About 0.25 kg per week |
| Lose steadily | TDEE − 500 | About 0.5 kg per week |
| Gain muscle | TDEE + 250 | About 0.25 kg per week with training |
A deficit of 500 kcal a day equals about 3,500 kcal a week, roughly the energy in 0.45 kg of body fat. The calorie deficit calculator and calorie surplus calculator turn a target date into a daily figure. Very low intakes, under about 1,200 kcal for women or 1,500 for men, are hard to sustain and usually need medical supervision.
How accurate is the estimate?
For most adults Mifflin-St Jeor lands within 10% of measured resting metabolism, but individual variation is real: two people with identical inputs can differ by 200 to 300 kcal a day. The activity multiplier is the bigger source of error, because people tend to overrate how active they are. The reliable check is the scale. Eat at the calculated level for two to three weeks; if your weight drifts, adjust intake by 100 to 200 kcal and repeat.
Very muscular people are underestimated by the formula, and people with high body fat are overestimated, because the equation uses total weight rather than lean mass. In those cases the Katch-McArdle calculator, which starts from lean body mass, gives a better BMR. The body fat calculator and lean body mass calculator provide the input it needs.
Common mistakes
- Entering pounds or inches. The fields expect kilograms and centimetres. 176 lb is 80 kg; 5 ft 10 in is 178 cm.
- Picking “very active” for a gym habit. Three one-hour sessions a week is moderately active. Reserve very active for daily hard training or manual work.
- Treating the result as fixed. TDEE falls as you lose weight; recalculate every 5 kg.
- Counting exercise twice. If you choose an activity level, do not add workout calories from a fitness tracker on top.
Related tools
The BMR calculator shows the resting figure alone. The BMI calculator and healthy weight calculator help decide whether a change in weight is appropriate, and the body recomposition calculator plans simultaneous fat loss and muscle gain. Once you have a calorie target, the macronutrient calculator splits it into carbohydrate, protein and fat.
External references
- Mifflin et al., 1990: A new predictive equation for resting energy expenditure
- CDC: healthy weight and energy balance
Frequently asked questions
Is this the number of calories I should eat?
It is the number that keeps your weight steady at your current activity. Eat less to lose weight, more to gain.
Why is the female formula 166 kcal lower?
On average women carry a higher proportion of body fat, which uses less energy than muscle. The constants in the equation reflect that difference in the study population.
Does the calculator work for teenagers?
Mifflin-St Jeor was developed for adults aged 19 to 78. Growing adolescents need more energy than it predicts.
Should I recalculate after losing weight?
Yes. Every 5 kg lost lowers BMR by roughly 50 kcal, and the activity share shrinks too. Update the inputs and adjust your intake.
Which is better, this calculator or a fitness tracker?
Trackers estimate exercise calories with wide error margins. The formula plus the scale test above is usually more reliable for setting daily intake.