Calorie Calculator

What is the Calorie Calculator?

The Calorie Calculator estimates how many calories your body uses in a day and turns that into targets for losing, keeping or gaining weight. Enter age, sex, height, weight and activity level; it computes your basal metabolic rate (BMR) with the Mifflin-St Jeor equation, multiplies by an activity factor to get total daily energy expenditure (TDEE), and shows calorie targets for a slow, moderate and faster change. It runs in your browser and stores nothing.

How to use it

1. Enter your details in metric or imperial.
2. Pick the activity level that honestly matches a typical week, not your best week.
3. Read your BMR, your maintenance calories, and the targets.

The numbers explained

BMR is what you would burn lying still all day. TDEE adds movement: sedentary is BMR times 1.2, light activity 1.375, moderate 1.55, very active 1.725. A deficit of 500 calories a day is roughly half a kilogram a week; a 250 deficit is gentler and easier to keep. Most people overestimate their activity level by one step, which is why a “moderate” plan often stalls. Where the equation comes from, why it replaced Harris-Benedict, and how to correct the estimate against real-world results is in how many calories do you actually need?

Using the estimate well

• Treat the number as a starting point; track weight for two weeks and adjust by 100 to 200 calories if it is not moving as expected.
• Do not go below about 1,200 (women) or 1,500 (men) without medical advice.
• Protein at 1.6 to 2.2 g per kg of body weight protects muscle in a deficit.
• Recalculate after every 5 kg change; needs fall as weight falls.

Related tools

Check your BMI with the BMI Calculator, convert lb to kg with the Unit Converter, and work out percentages of a target with the Percentage Calculator.

Frequently asked questions

Which formula does it use?

Mifflin-St Jeor, the equation most dietitians use because it is the most accurate for the general population.

Does it account for body fat?

No. If you know your body fat percentage, the Katch-McArdle formula in the guide is more precise for very lean or very muscular people.

Is this medical advice?

No. It is an estimate for healthy adults. Talk to a doctor or dietitian before a large change, and always if you are pregnant, under 18 or have a medical condition.