For educational purposes only. Not personalised health advice. This calculator has not been reviewed by a registered dietitian, physician or exercise physiologist. Results are population estimates and can be wrong for you individually. Speak to a qualified professional before acting on them, particularly if you are pregnant, under 18, managing a medical condition, or have a history of disordered eating.
Calorie Calculator
This calculator estimates the calories you burn in a typical day, your total daily energy expenditure (TDEE): the energy your body uses at rest plus the energy of daily movement and exercise. It is aimed at anyone setting a starting point for weight loss, weight gain or maintenance, and at coaches and dietitians who want a defensible first estimate to adjust from. Eating roughly this many calories a day should hold your weight steady; eating consistently below it should reduce weight, and above it should increase weight.
The estimate uses the Mifflin-St Jeor equation to predict resting metabolic rate, then multiplies it by an activity factor. Mifflin-St Jeor was derived from healthy adults and is the equation most commonly recommended for general use, but it is a population average: two people with identical height, weight, age and sex can genuinely differ by several hundred calories a day. Treat the number as a hypothesis to test over two to three weeks, not a measured fact.
When this estimate is not appropriate: it is not validated for children and adolescents, for pregnancy or breastfeeding, for people with very high or very low body fat (it uses total weight, so it over-estimates for people carrying a lot of fat mass and under-estimates for very muscular people), or for anyone with a condition or medication that alters metabolism. The most common mistakes are entering height in inches rather than centimetres, and over-stating activity level: most people who describe themselves as "very active" are closer to moderately active once desk hours are counted. If you are managing a medical condition, an eating disorder, or are pregnant, use this only alongside advice from a qualified clinician or registered dietitian.
For a 35 year old woman, 60 kg and 165 cm, who is sedentary, estimated maintenance is 1554.3 kcal/day.
Applies to: healthy adults. Formula source: Mifflin MD, St Jeor ST et al., "A new predictive equation for resting energy expenditure in healthy individuals", American Journal of Clinical Nutrition 1990;51(2):241-247. Activity factors and general dietary reference context: USDA DRI Calculator. Checked 2026-06-23.
The formula
maintenance calories = ((10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5 for men or - 161 for women) x activity factor
Worked example
A 35 year old woman, 60 kg and 165 cm, who sits at a desk and does little formal exercise (sedentary, factor 1.2):
- Resting metabolic rate (Mifflin-St Jeor): (10 x 60) + (6.25 x 165) - (5 x 35) - 161 = 600 + 1031.25 - 175 - 161 = 1,295.25 kcal/day
- Multiply by the sedentary activity factor 1.2: 1,295.25 x 1.2 = 1,554.30 kcal/day
- So maintenance is about 1,554 kcal/day. If she moved to moderately active (1.55) instead, maintenance would rise to about 2,008 kcal/day, a difference of over 450 calories from the activity factor alone.
This worked example is one of the automated golden-value tests this calculator must pass before it can publish.
What this assumes
- You are a healthy adult. Mifflin-St Jeor was derived from healthy adults and is not validated for children, adolescents, pregnancy or breastfeeding.
- Body composition is close to average for your height and weight. The equation uses total body weight, so it tends to over-estimate for people carrying a high proportion of fat mass and under-estimate for very muscular people.
- The activity factor you chose reflects a typical week, including work. Activity factors are broad bands, and this is the largest single source of error in the result.
- The output is an estimated maintenance requirement, not a prescription. It is general information and is not medical or dietetic advice.
Reading a calorie target honestly
A calorie calculator estimates your total daily energy expenditure, or TDEE: your resting metabolism plus the energy of movement, digestion and exercise. It is a well-educated starting estimate, not a measured fact, and individual metabolism varies enough that two people with identical stats can differ by a few hundred calories a day.
The honest way to use the number is as a hypothesis. Eat to the estimate for two to three weeks, track weight as a weekly average rather than daily (water shifts hide the signal), then adjust by 100 to 200 calories based on what actually happened. This closed loop beats any formula because it measures you, not an average person.
Two myths cost people the most progress. The first is that a deficit works forever at the same size; as you lose weight your maintenance falls, so plateaus are the body doing exactly what physics predicts, and the fix is to recalculate, not to crash lower. The second is precision theatre: chasing a target to the single calorie while ignoring the 20 to 30 percent margin in food labels and activity estimates. Consistency at a sensible deficit outperforms accuracy that cannot be measured.
Frequently asked questions
What formula does this use?
Resting metabolic rate from the Mifflin-St Jeor equation, (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5 for men or - 161 for women, multiplied by an activity factor from 1.2 (sedentary) to 1.9 (extra active). The equation comes from Mifflin and St Jeor's 1990 paper in the American Journal of Clinical Nutrition, linked in the sources below.
How accurate is it for me personally?
Mifflin-St Jeor predicts resting metabolic rate within about 10 percent for most healthy adults, but individual variation is real: two people with identical inputs can differ by several hundred calories a day. Use the number as a starting hypothesis, hold it for two to three weeks, track weight as a weekly average, then adjust by 100 to 200 calories based on what actually happened.
Why did my maintenance calories fall as I lost weight?
Because maintenance depends on your current body weight. As you lose weight the same equation returns a lower number, so a deficit that worked at the start becomes maintenance later. Recalculate every few kilograms rather than cutting further.
Should I use this if I am pregnant, under 18, or being treated for a medical condition?
No. The equation is not validated for children, adolescents, pregnancy or breastfeeding, and conditions or medications affecting metabolism can shift requirements substantially. Speak to a qualified clinician or registered dietitian instead.
Official sources and verification
- Method: USDA DRI Calculator, checked 2026-06-23.
This content is provided for educational purposes only and has not been reviewed by a qualified specialist in this field. See our methodology. General information, not professional advice.