How this calorie calculator works
- It estimates your basal metabolic rate (BMR), the energy you use at rest, with the Mifflin-St Jeor equation.
- It multiplies BMR by an activity factor to estimate your total daily energy expenditure (TDEE): the calories you burn in a typical day.
- It shows targets for maintaining your weight, and for gradual loss or gain of about 0.25 to 0.5 kg (½ to 1 lb) a week.
Men: BMR = 10W + 6.25H − 5A + 5 · Women: BMR = 10W + 6.25H − 5A − 161
W is weight in kg, H height in cm and A age in years. Research reviews have found Mifflin-St Jeor to be the most accurate of the common equations for most adults.
Worked example: a 35-year-old man, 175 cm and 75 kg: BMR = 750 + 1,093.75 − 175 + 5 = 1,674 kcal. Moderately active (× 1.55), he needs about 2,590 kcal a day to maintain his weight.
What official guidance says
| Source | Guidance |
|---|---|
| NHS (UK) | Around 2,500 kcal a day for men and 2,000 kcal for women to maintain weight; aim to lose 0.5 to 1 kg (1 to 2 lb) a week if overweight |
| Dietary Guidelines for Americans | Roughly 2,000–3,000 kcal a day for adult men and 1,600–2,400 for adult women, depending on age and activity |
| Voedingscentrum (NL) | Personal energy needs depend on age, sex, height, weight and activity; gradual change is recommended |
Slow and steady is safer and lasts longer. Very low calorie diets should only be followed under medical supervision.
For that reason the calculator does not show targets below 1,200 kcal a day for women or 1,500 kcal for men, levels many health organisations advise not going below without supervision.
Medical note: these are estimates; real needs can differ by 10% or more. If you have a health condition, are pregnant or breastfeeding, or have a history of disordered eating, please speak to your doctor or a registered dietitian before changing what you eat. In the UK, Beat (beateatingdisorders.org.uk) offers support; in the US, the National Alliance for Eating Disorders helpline.
Sources
- Mifflin MD, St Jeor ST et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990
- NHS, Understanding calories and Start losing weight
- US Department of Agriculture and HHS, Dietary Guidelines for Americans, 2020–2025
- Voedingscentrum, Hoeveel calorieën heb ik nodig?
Frequently asked questions
How many calories do I need a day?
It depends on your age, sex, size and activity. As a rough guide, the NHS suggests about 2,500 kcal for men and 2,000 kcal for women. The calculator gives a personal estimate.
What is TDEE?
Total daily energy expenditure: the calories you burn in a day, including rest, digestion and activity. It is your BMR multiplied by an activity factor.
How many calories should I cut to lose weight?
A deficit of about 500 kcal a day leads to roughly 0.5 kg (1 lb) of weight loss a week for many people, in line with NHS advice to aim for 0.5 to 1 kg a week.
Which activity level should I choose?
Most people overestimate. If you have a desk job and exercise two or three times a week, choose lightly or moderately active, then adjust based on how your weight changes over a few weeks.