How to use the Calorie Calculator
- Choose your units and sex, then enter your age, height and weight.
- Pick the activity level that matches a normal week.
- Read your maintenance calories and the targets for gentle loss or gain.
How it works
The calculator first estimates your basal metabolic rate (BMR), the energy your body uses at rest, with the Mifflin-St Jeor equation. It then multiplies BMR by an activity factor to estimate total daily energy expenditure (TDEE), which is roughly the calories that keep your weight stable.
A deficit of about 500 kcal a day is commonly linked to losing around 0.5 kg (1 lb) a week, though real results vary as the body adapts. Targets never go below 1,200 kcal for women or 1,500 kcal for men, because eating less than that without medical supervision is generally not advised. The results are estimates for healthy adults; if you are pregnant, under 18 or managing a health condition, ask a doctor or registered dietitian.
Formula
Men: BMR = 10 × kg + 6.25 × cm − 5 × age + 5 Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161 TDEE = BMR × activity factor
Example
A 34-year-old woman, 5 ft 6 in and 150 lb, has a BMR of about 1,397 kcal. With light exercise (factor 1.375) her maintenance is about 1,920 kcal a day.
Activity factors
| Activity level | Factor |
|---|---|
| Mostly sitting, little exercise | 1.2 |
| Light exercise 1–3 days a week | 1.375 |
| Moderate exercise 3–5 days a week | 1.55 |
| Hard exercise 6–7 days a week | 1.725 |
| Physical job plus training | 1.9 |
Frequently asked questions
What is TDEE?
Total daily energy expenditure: the calories you burn in a day from resting metabolism, digestion and movement combined.
How accurate is this?
Mifflin-St Jeor is one of the better-performing formulas in studies, but individuals can differ from the estimate by 10% or more. Track your weight for a few weeks and adjust.
Which activity level should I pick?
Choose by your typical week, not your best one. Most office workers who exercise a few times a week fit 'light' or 'moderate'.
Can teenagers use it?
No. Teenagers are still growing and have different needs, so they should get advice from a doctor.
Last reviewed October 20, 2026. Spotted an error? Tell us.