How this calorie calculator works
It uses the Mifflin-St Jeor equation, a widely used formula for estimating basal metabolic rate (BMR), the energy your body needs at complete rest. For men: BMR = 10×kg + 6.25×cm − 5×age + 5. For women: BMR = 10×kg + 6.25×cm − 5×age − 161. Your BMR is then multiplied by an activity factor (from 1.2 for a sedentary day up to 1.9 for very hard daily training) to estimate total daily energy expenditure (TDEE), the calories you burn in a normal day.
Using the results
Eating at your TDEE tends to keep your weight stable. A moderate deficit of about 500 calories a day is commonly associated with roughly a pound (0.5 kg) of weight loss per week, and a surplus of the same size with gradual gain. These are rules of thumb: the body adapts, so progress rarely follows a perfectly straight line.
Tips for choosing your activity level
- Pick the level that matches your average week, not your best week.
- If you have a desk job and work out three times a week, "Light" or "Moderate" is usually accurate.
- When unsure, choose the lower level and adjust after tracking your weight for a few weeks.
Important limits
Calorie calculators cannot see your body composition, medical conditions or medications. They are not suitable for pregnancy, breastfeeding or under-18s. See a healthcare professional before starting an aggressive diet.
Frequently asked questions
How many calories should I eat a day?
Your maintenance calories shown above are the starting point. To lose weight, eat somewhat below that number, and to gain weight, eat somewhat above it.
What is BMR?
Basal metabolic rate is the number of calories your body uses at rest to keep you alive: breathing, circulation and cell repair. It usually makes up the largest share of daily calorie burn.
Is Mifflin-St Jeor accurate?
It is considered one of the more reliable equations for the general population, but it is still an estimate and can be off by a few hundred calories for some people.
What is the safest rate of weight loss?
Many health organizations suggest around 1 to 2 pounds (0.5 to 1 kg) per week at most. Slower, steady loss is easier to maintain.