How to use the calorie calculator
Enter your age, sex, weight, height and activity level. The calculator gives you your BMR (calories burned at rest) and TDEE (total daily energy expenditure including activity). Then pick a goal — lose, maintain or gain — and it adjusts the daily target accordingly.
What is BMR?
Basal Metabolic Rate is the number of calories your body burns at complete rest — just to stay alive. Breathing, circulating blood, repairing cells, regulating temperature. Even if you stayed in bed all day, you'd burn this much.
What is TDEE?
Total Daily Energy Expenditure is your BMR multiplied by an activity factor. It includes everything you actually do in a day: walking, working, exercising, digesting food. It's the total calories you burn, and the number you need to eat to maintain your current weight.
The Mifflin-St Jeor equation
This calculator uses the Mifflin-St Jeor formula, which is the most accurate for the general population:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Then TDEE = BMR × activity factor.
Activity multipliers
| Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, little or no exercise |
| Lightly active | 1.375 | Light exercise 1–3 days/week |
| Moderately active | 1.55 | Moderate exercise 3–5 days/week |
| Very active | 1.725 | Hard exercise 6–7 days/week |
| Extra active | 1.9 | Physical job + hard training |
Calorie deficit for weight loss
One kilogram of body fat equals roughly 7,700 calories. So a deficit of:
- 250 calories/day — 0.25 kg loss per week
- 500 calories/day — 0.5 kg loss per week
- 1,000 calories/day — 1 kg loss per week
Most guidelines recommend 0.5 to 1 kg per week. Faster loss tends to rebound and strips muscle. Never go below your BMR for extended periods — that can slow your metabolism and cause other health issues.
Calorie surplus for muscle gain
Muscle gain is slower than fat loss. A surplus of 250 to 500 calories per day supports steady gains without excessive fat accumulation. Combined with resistance training and adequate protein (1.6 to 2.2 g per kg of body weight), you can gain 0.25 to 0.5 kg of muscle per month.
Macronutrients
- Protein — 4 calories per gram. Essential for muscle repair and satiety.
- Carbohydrates — 4 calories per gram. Primary fuel for training and brain function.
- Fat — 9 calories per gram. Hormone production, vitamin absorption, satiety.
The calculator offers several macro splits — balanced, high-protein, low-carb, keto, and vegetarian. Pick one that fits your preferences and adherence.
Common questions
What is BMR?
Basal Metabolic Rate is the number of calories your body burns at complete rest to maintain basic functions like breathing, circulation and cell repair.
What is TDEE?
Total Daily Energy Expenditure is BMR multiplied by an activity factor. It's the total calories you burn in a typical day including exercise and daily movement.
How many calories to lose weight?
A deficit of 500 calories per day produces roughly 0.5 kg of fat loss per week. Most guidelines suggest 0.5 to 1 kg per week maximum for sustainable weight loss.
How many calories to gain muscle?
A surplus of 250 to 500 calories per day supports muscle gain with minimal fat accumulation. Combined with resistance training and adequate protein.
How accurate is this calculator?
It's a good estimate for most people. Actual calorie needs vary with genetics, body composition, medication, hormonal state and how intensely you actually train. Use the number as a starting point and adjust after two weeks of tracking.
Do I need to count calories forever?
No. Most people use a calculator like this for 4 to 12 weeks to learn portion sizes and calorie awareness. After that, you can eat intuitively.
Does the equation differ for athletes?
Yes. Very muscular athletes may need more calories than the equation predicts, because muscle burns more at rest. If you're very lean and muscular, add 5 to 10%.
Is my data saved?
Your inputs are stored only in your browser's local storage. Nothing is sent to any server.