Calorie Calculator
Free online calorie calculator using the Mifflin-St Jeor equation. 100% client-side, no signup required.
Loading tool...
What is Calorie Calculator?
A Calorie Calculator is a free online tool that estimates your daily calorie needs using the Mifflin-St Jeor equation — the most accurate formula for calculating Basal Metabolic Rate (BMR). Simply enter your age, gender, height, weight, and activity level to get your BMR, Total Daily Energy Expenditure (TDEE), and personalized calorie targets for weight loss, maintenance, and weight gain. All calculations happen 100% in your browser with no data sent to any server.
Key Benefits
- Science-based BMR and TDEE estimation using the validated Mifflin-St Jeor equation
- Five activity levels from sedentary to extra active for accurate daily calorie needs
- Multiple calorie targets: weight loss (-500), mild loss (-250), maintenance (TDEE), and weight gain (+500)
- Supports both metric (kg/cm) and imperial (lb/in) unit systems
- 100% client-side and private — no data uploaded, no signup required
Common Use Cases
- •Plan a weight loss diet by setting a safe calorie deficit of 250-500 calories below TDEE
- •Calculate maintenance calories for stable weight management without dieting
- •Determine a calorie surplus for muscle gain and bulking cycles
- •Estimate BMR for understanding your baseline metabolic rate and energy needs
- •Track daily calorie budget for general fitness and health awareness
How to Use the Calorie Calculator
- Enter your details: Input your age, sex, height, and weight. Switch between metric (kg/cm) and imperial (lb/in) units using the toggle.
- Select your activity level: Choose the activity level that best matches your lifestyle — from sedentary (desk job) to extra active (athlete).
- Click Calculate: Press the Calculate button to instantly see your BMR, TDEE, and calorie targets for weight loss, maintenance, and weight gain.
- Copy or save your results: Use the Copy button to save all your calorie targets to the clipboard, then paste them into a fitness journal or app.
Key Features
- Mifflin-St Jeor BMR calculation - the most accurate formula available
- 5 activity levels from sedentary to extra active for precise TDEE estimation
- Shows BMR, TDEE, weight loss, mild loss, and weight gain calorie targets
- Supports both metric (kg/cm) and imperial (lb/in) unit systems
- Visual result cards with color-coded calorie targets for easy comparison
- 100% client-side with no data upload - your health data stays private
Frequently Asked Questions
How accurate is the Mifflin-St Jeor equation for calculating BMR?
The Mifflin-St Jeor equation is considered one of the most accurate BMR formulas, with studies showing it estimates resting energy expenditure within ±10% of measured values in most healthy adults. It was developed in 1990 and has since been validated across multiple populations, outperforming the older Harris-Benedict equation.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just keeping your heart beating, lungs breathing, and organs functioning. TDEE (Total Daily Energy Expenditure) multiplies your BMR by an activity factor (1.2 for sedentary to 1.9 for extra active) to estimate your actual daily calorie burn including movement, exercise, and digestion.
How many calories should I eat to lose weight?
A safe, sustainable calorie deficit is 250-500 calories below your TDEE, which typically leads to 0.5-1 lb (0.25-0.5 kg) of fat loss per week. The calculator shows both a mild loss (-250 kcal) and standard weight loss (-500 kcal) target. Avoid going below your BMR for extended periods, as this can slow metabolism and cause nutrient deficiencies.
Can I use this calorie calculator for weight gain and muscle building?
Yes. The calculator provides a weight gain target of TDEE + 500 calories, which is a common surplus for lean muscle gain. For bulking, aim for this surplus and consume adequate protein (1.6-2.2 g per kg of body weight). The tool is 100% client-side, so your data never leaves your browser.