CALCULATOR · Health
Calorie Calculator
Estimate your basal metabolic rate and daily calorie needs with the Mifflin–St Jeor equation, plus targets for losing, maintaining or gaining weight.
Show formula
Method reviewed:Mifflin–St Jeor resting-metabolic-rate equation (1990) with standard activity multipliers · reviewed August 2026
Inputs
Light exercise 1–3 days a week.
Result
Your result appears here
Enter Age and the result fills in as you type.
How it works
- Choose metric or imperial units and enter your sex, age, height and weight.
- Pick the activity level that matches a typical week, not your best week.
- Read your basal metabolic rate, daily calorie needs and the targets for losing, holding or gaining weight.
Frequently asked questions
Which equation is used?
Mifflin–St Jeor (1990), which the Academy of Nutrition and Dietetics considers the most accurate predictive equation for healthy adults. Daily needs are that figure multiplied by a standard activity factor from 1.2 to 1.9.
How accurate is the estimate?
Predictive equations typically land within about 10% of measured energy expenditure for most people, but individuals vary. Use the number as a starting point and adjust based on what actually happens over a few weeks.
Why is 500 kcal a day the largest deficit shown?
Roughly 500 kcal per day corresponds to about half a kilogram of weight change per week, which is a commonly cited sustainable pace. Larger deficits are harder to maintain and more likely to cost muscle.
Why won’t it show a very low calorie target?
Targets are held at a floor of 1,200 kcal for women and 1,500 for men. Intakes below that are a clinical intervention that needs medical supervision, so this tool will not suggest one.
Can I use this during pregnancy, while breastfeeding, or for a child?
No. Energy needs in those situations follow different guidance entirely. Please speak to a doctor or a registered dietitian.
Examples
- A 30-year-old man, 180 cm and 80 kg, moderately active
- BMR 1,780 kcal and about 2,759 kcal a day to maintain his weight (activity factor 1.55). Losing 0.5 kg a week means about 2,259 kcal a day.
- A 35-year-old woman, 165 cm and 60 kg, lightly active
- BMR 1,295 kcal and about 1,781 kcal a day to maintain her weight (activity factor 1.375).
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