Your maintenance calories are the calories you burn in a day, so eating that many keeps your weight steady. They are your BMR (calories burned at complete rest) multiplied by an activity factor from 1.2 for a desk job to 1.9 for heavy physical work. A 30-year-old man of 175 cm and 78 kg who exercises a little needs about 2,380 kcal a day.
Enter your sex, age, height and weight, and choose your activity level. The calculator shows your BMR, your total daily energy expenditure (TDEE) and a daily target for each weekly weight change, with a warning if a target is too low to follow without medical advice.
How to calculate BMR and TDEE
The calculator uses the Mifflin-St Jeor equation, published in 1990. A 2005 review by Frankenfield and colleagues for the American Dietetic Association found it the most reliable of the common equations for healthy adults.
- Men: BMR = 10 × weight in kg + 6.25 × height in cm − 5 × age + 5
- Women: BMR = 10 × weight in kg + 6.25 × height in cm − 5 × age − 161
Then TDEE = BMR × activity factor.
Worked example
A man aged 30, 175 cm tall, weighing 78 kg, who exercises 1 to 3 days a week.
| Step | Working | Result |
|---|---|---|
| Weight part | 10 × 78 | 780 |
| Height part | 6.25 × 175 | 1,093.75 |
| Age part | 5 × 30 | minus 150 |
| Men's constant | plus 5 | |
| BMR | 780 + 1,093.75 − 150 + 5 | 1,729 kcal |
| TDEE | 1,728.75 × 1.375 | 2,377 kcal |
To lose about 0.5 kg a week he would eat around 550 kcal less, about 1,830 kcal a day.
Maintenance calories by activity level
For the same man, BMR 1,729 kcal. Choosing the right level matters more than any other input: most people who work at a desk are sedentary or lightly active, even if they walk a little.
| Activity level | Factor | Maintenance, kcal a day |
|---|---|---|
| Sedentary: desk job, little or no exercise | 1.2 | 2,075 |
| Lightly active: exercise 1 to 3 days a week | 1.375 | 2,377 |
| Moderately active: exercise 3 to 5 days a week | 1.55 | 2,680 |
| Very active: hard exercise 6 to 7 days a week | 1.725 | 2,982 |
| Extra active: physical job plus training | 1.9 | 3,285 |
How many calories to lose weight
A kilogram of body fat holds roughly 7,700 kcal, so a daily deficit of about 550 kcal gives around 0.5 kg a week. NICE, the UK health guideline body, recommends a deficit of about 600 kcal a day for adults trying to lose weight, aiming for 0.5 to 1 kg a week.
Weight loss slows as you get lighter, because a smaller body burns fewer calories. Recalculate after every few kilos.
Second example: a smaller, less active person
A woman aged 45, 5 ft 2 in (157.5 cm), 65 kg, with a desk job and little exercise:
- BMR = 650 + 984.25 − 225 − 161 = 1,248 kcal
- Maintenance at 1.2 = 1,498 kcal
- Losing 0.25 kg a week: about 1,220 kcal a day
- Losing 0.5 kg a week would need about 950 kcal a day, which is too low without medical supervision
For her, adding daily walking to reach the lightly active level (maintenance about 1,716 kcal) is a safer way to create a larger deficit than eating less. Harvard Health Publishing suggests women should not go below about 1,200 kcal a day and men below about 1,500 without medical supervision, so the calculator flags targets under those figures.
How many calories to gain weight
To gain weight steadily, eat above maintenance. A surplus of about 275 kcal a day is roughly 0.25 kg a week, and 550 kcal about 0.5 kg. If you want the gain to be muscle rather than fat, pair it with strength training and enough protein. If you are underweight on the BMI calculator and not sure why, see a doctor before trying to gain.
Who should not use this calculator
The equation is for adults. Do not use it to set a diet for:
- children and teenagers under 18, who need extra energy to grow;
- pregnant or breastfeeding women, whose needs are higher;
- anyone with diabetes on insulin or tablets that can cause low blood sugar, kidney disease, or an eating disorder, unless a doctor or dietitian agrees;
- very muscular athletes, for whom Mifflin-St Jeor tends to underestimate.
To check a target weight first, use the ideal weight calculator.
This calculator gives an estimate from a published formula. It does not diagnose any condition and is not a substitute for a doctor. Talk to a doctor before making decisions about your health, diet or treatment.
Calorie questions
What are maintenance calories?
Maintenance calories are the number of calories you burn in a day, including rest, digestion, work and exercise. Eating that amount keeps your weight steady. It is the same thing as TDEE. For most adults it falls between about 1,600 and 3,000 kcal, depending on size, sex, age and activity.
How do I calculate my BMR?
Use the Mifflin-St Jeor equation: 10 × weight in kg, plus 6.25 × height in cm, minus 5 × age, then add 5 for men or take away 161 for women. A 30-year-old woman of 160 cm and 60 kg has a BMR of 600 + 1,000 − 150 − 161 = 1,289 kcal.
What is the difference between BMR and TDEE?
BMR is what your body burns lying completely still, for breathing, circulation and keeping warm. TDEE adds everything else: walking, work, exercise and digesting food. TDEE is BMR multiplied by an activity factor, from 1.2 for sedentary people to 1.9 for very physical jobs plus training.
How many calories should I eat to lose 1 kg a week?
About 1,100 kcal a day below your maintenance, because 1 kg of fat is roughly 7,700 kcal. That is a large deficit, and for smaller or less active people it takes intake below safe levels. NICE suggests aiming for 0.5 to 1 kg a week with a deficit of about 600 kcal a day.
Is Mifflin-St Jeor better than Harris-Benedict?
For most healthy adults, yes. The Harris-Benedict equation dates from 1919 and tends to overestimate needs today. A 2005 review found Mifflin-St Jeor predicted resting energy use within 10% of measured values in more people than the other common equations. No equation is exact for one person.
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Last reviewed 30 September 2026. Results are estimates; official notices always take precedence.