Calorie Calculator
Calculate your BMR and TDEE using the Mifflin-St Jeor formula for accurate daily calorie targets.
How to use Calorie Calculator
This calorie calculator estimates how many calories you should eat each day to lose weight, maintain your current weight or build muscle. It uses the Mifflin-St Jeor equation to calculate your Basal Metabolic Rate (BMR), multiplies by your activity level to find your Total Daily Energy Expenditure (TDEE), then adjusts by your goal: a 500 kcal deficit for weight loss, zero change for maintenance, or a 500 kcal surplus for muscle gain.
- Select your gender.
- Enter your age, height in centimetres and weight in kilograms.
- Choose your activity level from the dropdown.
- Pick your goal: Lose Weight, Maintain Weight or Gain Weight.
- Your daily calorie target updates instantly — no button press needed.
Your data never leaves your device — 100% private processing.
How calories are calculated
The Mifflin-St Jeor formula gives your resting calorie burn (BMR). Multiplying by an activity factor (1.2 to 1.9) gives TDEE. Adding or subtracting a goal adjustment gives your target: −500 kcal/day creates a deficit that results in approximately 0.5 kg of weight loss per week (since roughly 7,700 kcal = 1 kg of fat). The +500 kcal surplus supports muscle protein synthesis when combined with resistance training.
Why calorie counting is a starting point, not a perfect science
Food labels carry up to ±20% error, and individual calorie absorption varies with gut microbiome, food processing and meal composition. The 500 kcal deficit rule works on average, but individuals may need 400–700 kcal below TDEE depending on adaptive thermogenesis. Use this estimate as a starting target, weigh yourself weekly and adjust by 100–200 kcal every 2–3 weeks if weight is not moving in the expected direction.
Glossary
- BMR
- Basal Metabolic Rate — calories burned at rest for survival.
- TDEE
- Total Daily Energy Expenditure — total calories burned per day with activity.
- Calorie deficit
- Eating fewer calories than you burn, causing the body to use stored fat.
- Calorie surplus
- Eating more calories than you burn, enabling muscle growth when training.
Related reading
Frequently Asked Questions
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Why use Calorie Calculator?
- Based on widely-accepted clinical and scientific formulas
- No personal data stored — all calculations run locally
- Supports both metric and imperial units
- Results include actionable recommendations
Common use cases
- Calculate BMI before a doctor's appointment
- Estimate daily calorie needs for a weight loss goal
- Track ideal body weight range for a fitness plan
- Calculate pregnancy due date
- Find out your recommended water intake based on body weight
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