Calorie Calculator — BMR & TDEE Estimate, Free & Private
Estimate your daily calorie needs using the Mifflin-St Jeor equation — the most clinically validated formula for BMR. Multiply by your activity level to get TDEE (Total Daily Energy Expenditure). Works for metric and imperial. Runs in your browser — your personal data never leaves your device.
How to use this tool
- Enter your age, sex, height, weight, and activity level.
- See your estimated daily calorie needs.
- Adjust activity level to see different calorie targets.
About Calorie Calculator
The Calorie Calculator estimates how many calories your body burns in a day so you can plan eating for maintenance, weight loss, or weight gain. You enter your sex, weight in kilograms, height in centimetres, and age in years, then pick an activity level from a five-step scale. The result shows two numbers: your basal metabolic rate, which is the energy your body uses at complete rest, and your total daily energy expenditure, which is the realistic figure most people care about.
The estimate is built on the Mifflin-St Jeor equation, widely regarded as the most accurate of the common predictive formulas for resting metabolism. It computes a base value of ten times your weight in kilograms plus 6.25 times your height in centimetres minus five times your age, then adds five for men or subtracts 161 for women. That basal rate is multiplied by an activity factor: 1.2 for sedentary, 1.375 for light exercise one to three days a week, 1.55 for moderate exercise three to five days, 1.725 for active six to seven days, and 1.9 for very active or physically demanding jobs.
To turn the number into a plan, the tool also shows a simple target above and below maintenance. A deficit of about 500 calories a day corresponds to losing roughly half a kilogram of fat per week, since a kilogram of body fat stores close to 7,700 calories; the matching surplus supports gradual gain. These are starting estimates. Real expenditure varies with body composition, genetics, sleep, stress, and how honestly you classify your activity, so treat the figure as a hypothesis to test rather than a fixed truth.
This is general informational guidance, not medical or dietary advice, and the calculation runs entirely in your browser so your personal details are never sent anywhere. The best way to use it is to start at the suggested intake, weigh yourself over two to three weeks, and adjust by 100 to 200 calories based on the actual trend. Anyone who is pregnant, breastfeeding, managing a medical condition, or considering a large change should speak with a doctor or registered dietitian first.
Frequently Asked Questions
- Which formula does this calculator use?
- It uses the Mifflin-St Jeor equation to estimate basal metabolic rate, then multiplies by an activity factor to get total daily energy expenditure. Mifflin-St Jeor is considered the most reliable of the common prediction equations for the general population.
- What is the difference between BMR and TDEE?
- BMR (basal metabolic rate) is the energy your body uses at complete rest just to keep organs running. TDEE (total daily energy expenditure) is BMR multiplied by an activity factor and represents your real-world daily burn including movement and exercise. TDEE is the number to aim your intake at for maintenance.
- How do the activity levels map to calories?
- Sedentary multiplies BMR by 1.2, light activity (1 to 3 days of exercise per week) by 1.375, moderate (3 to 5 days) by 1.55, active (6 to 7 days) by 1.725, and very active (hard daily training or a physical job) by 1.9. Most people overestimate their level, so choose conservatively if unsure.
- Where do the lose and gain numbers come from?
- The tool subtracts and adds 500 calories from your maintenance figure. A daily 500-calorie deficit roughly equals losing half a kilogram of fat per week, because a kilogram of body fat holds about 7,700 calories. The same surplus supports steady weight gain.
- Does it accept imperial units?
- No. This calculator takes weight in kilograms, height in centimetres, and age in years. If you use pounds and inches, convert first: divide pounds by 2.205 for kilograms, and multiply inches by 2.54 for centimetres.
- How accurate is the estimate?
- It is a good starting point but only an estimate. Actual needs vary with muscle mass, genetics, hormones, sleep, and activity that is hard to quantify. The reliable approach is to eat at the suggested level for two to three weeks, track your weight trend, and adjust intake by 100 to 200 calories based on what actually happens.
- Is this medical or dietary advice?
- No. It is general informational guidance. If you are pregnant, breastfeeding, have a medical condition, or plan a significant dietary change, consult a doctor or registered dietitian before acting on the numbers.
- Is my data kept private?
- Yes. Everything is calculated in your browser and nothing is uploaded or stored, so your sex, weight, height, and age never leave your device.
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