Calorie Calculator
Estimate your daily calorie needs for maintenance, loss or gain.
All calculations happen locally in your browser — nothing is uploaded, stored or tracked.
Enter your details
Sex, age, height and weight.
Choose your activity level
From sedentary to extra active.
Read your targets
Maintenance, plus mild and moderate loss/gain targets.
What Is a Calorie Calculator?
A calorie calculator estimates how many calories your body needs each day. It first works out your Basal Metabolic Rate (BMR) — the energy your body burns at complete rest just to stay alive — using the Mifflin-St Jeor equation, then multiplies by an activity factor to get your Total Daily Energy Expenditure (TDEE).
The calculator also converts weight-loss goals into daily targets. Because roughly 7,700 kcal equals one kilogram of body fat, a 500 kcal daily deficit produces about 0.5 kg of weight loss per week.
The Mifflin-St Jeor Equation
BMR is then scaled by an activity factor: 1.2 (sedentary), 1.375 (light), 1.55 (moderate), 1.725 (very active) or 1.9 (extra active). The result is an estimate — real energy needs vary with muscle mass, genetics and hormones.
Limitations
Your data never leaves your device.
Every calculation on this site runs in your browser using vanilla JavaScript. Nothing is uploaded, stored or tracked.
- 100% local, client-side calculations
- No data stored on any server
- No tracking, no analytics, no ads scripts
- Works offline once loaded
Frequently Asked Questions
How many calories should I eat a day?
It depends on age, sex, height, weight and activity. This calculator estimates your maintenance calories from the Mifflin-St Jeor equation; eating roughly that amount keeps your weight stable.
How many calories to lose weight?
Create a deficit of about 500 kcal per day below maintenance to lose roughly 0.5 kg per week. The calculator shows the targets.
What is TDEE?
Total Daily Energy Expenditure — the total calories you burn in a day including activity, not just at rest.
Is the Mifflin-St Jeor equation accurate?
It is among the most accurate predictive equations for most adults, within about 10% for many people, but individual variation is real.
Do I need to count calories to lose weight?
Not necessarily, but knowing your target helps. Sustainable habits matter more than precision.