In short: A calorie calculator estimates daily energy needs (TDEE) from basal metabolic rate — using the Mifflin–St Jeor equation — multiplied by an activity factor.
About Calorie Calculator (BMR & TDEE)
Your basal metabolic rate (BMR) is the energy your body uses at complete rest to keep you alive — breathing, circulation, temperature. Your total daily energy expenditure (TDEE) adds everything else you do, from walking to training. TDEE is roughly the number of calories a day that keeps your weight stable.
This calculator uses the Mifflin–St Jeor equation, which studies have found to be among the more accurate formulas for estimating BMR in healthy adults, and multiplies it by a standard activity factor. It also shows a gentle deficit and surplus for reference. Treat the numbers as a starting point and adjust based on how your weight actually changes over a few weeks.
How to use Calorie Calculator (BMR & TDEE)
- Choose metric or imperial units.
- Enter sex, age, height and weight.
- Pick the activity level that best describes a typical week.
- Read your estimated BMR and daily calorie needs.
Examples
35 years, 168 cm, 65 kg: BMR ≈ 10×65 + 6.25×168 − 5×35 − 161 = 1,364 kcal; with moderate activity, TDEE ≈ 2,114 kcal.
45 years, 180 cm, 85 kg: BMR ≈ 1,755 kcal; sedentary TDEE ≈ 2,106 kcal.
Frequently asked questions
What is the Mifflin–St Jeor formula?
For men: 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. For women: the same with −161 instead of +5.
Which activity level should I choose?
Most people overestimate. If you have a desk job and exercise a few times a week, “Light” or “Moderate” is usually right.
Why is my real intake different from the estimate?
Metabolism varies between individuals, and food labels and fitness trackers are themselves approximate. Track your weight trend for a few weeks and adjust.
Is my data stored?
No. Everything is calculated in your browser.
Updated November 2026 · Free, no signup · How we build and test tools