Calorie Intake Calculator
This calculator estimates your daily calorie needs using the Mifflin-St Jeor equation, the formula recommended by most registered dietitians and validated in peer-reviewed research as the most accurate predictive equation for resting metabolic rate in most healthy adults. Enter your age, sex, weight in kilograms, height in centimetres, and your typical activity level. The calculator returns your basal metabolic rate (BMR), the calories you burn at rest; your total daily energy expenditure (TDEE), which is your maintenance intake; and three goal-based calorie targets. To lose approximately 0.5 kg per week, a deficit of around 550 kcal per day is needed (1 kg of fat is approximately 7,700 kcal, so 0.5 kg per week requires 3,850 kcal per week deficit, or 550 kcal per day). To gain approximately 0.25 kg per week (primarily lean mass when combined with resistance training), a modest surplus of around 275 kcal per day is recommended. These are estimates: individual responses vary, and you should adjust based on actual weight trends over two to four weeks. These figures are general guidance and are not a substitute for advice from a registered dietitian or healthcare provider.
BMR: -- kcal/day — Maintenance (TDEE): -- kcal/day
How BMR and TDEE are calculated
The Mifflin-St Jeor equation estimates BMR from sex, weight, height, and age. TDEE is BMR multiplied by an activity factor representing how much additional energy you burn through movement and exercise.
BMR (male) = 10 × weight (kg) + 6.25 × height (cm) - 5 × age + 5
BMR (female) = 10 × weight (kg) + 6.25 × height (cm) - 5 × age - 161
TDEE = BMR × activity multiplier
Activity multipliers:
Sedentary: 1.200 | Lightly active: 1.375 | Moderately active: 1.550
Very active: 1.725 | Extra active: 1.900
Lose 0.5 kg/week = TDEE - 550 kcal
Gain 0.25 kg/week = TDEE + 275 kcal
Worked example
30-year-old female, 70 kg, 170 cm, moderately active (1.55):
- BMR = 10 × 70 + 6.25 × 170 - 5 × 30 - 161 = 700 + 1,062.50 - 150 - 161 = 1,451.50 kcal/day
- TDEE = 1,451.50 × 1.55 = 2,249.83 kcal/day
- Lose 0.5 kg/week = 2,249.83 - 550 = 1,699.83 kcal/day
- Gain 0.25 kg/week = 2,249.83 + 275 = 2,524.83 kcal/day
Activity level guide
| Activity level | Multiplier | Typical description |
|---|---|---|
| Sedentary | 1.200 | Desk job, little or no intentional exercise |
| Lightly active | 1.375 | Light exercise or sport 1 to 3 days per week |
| Moderately active | 1.550 | Moderate exercise or sport 3 to 5 days per week |
| Very active | 1.725 | Hard exercise or sport 6 to 7 days per week |
| Extra active | 1.900 | Very hard exercise, physical labour job, or twice-daily training |
Calorie deficit and surplus: the key numbers
One kilogram of body fat stores approximately 7,700 kilocalories. This means:
- To lose 0.5 kg per week: create a deficit of 3,850 kcal per week, or approximately 550 kcal per day.
- To lose 1.0 kg per week: create a deficit of 7,700 kcal per week, or approximately 1,100 kcal per day (requires medical supervision for most people).
- To gain 0.25 kg per week (lean mass, combined with resistance training): add approximately 275 kcal per day.
These targets assume that weight change is proportional to calorie balance. In practice, water retention, hormonal fluctuations, and adaptation of metabolic rate mean that results vary. A realistic rate of fat loss for most adults is 0.25 to 0.5 kg per week.
Calorie intake: frequently asked questions
What is BMR and why does it matter?
Basal metabolic rate (BMR) is the number of kilocalories your body burns at complete rest over 24 hours, just to maintain basic functions such as breathing, circulation, and cell repair. It is the largest component of total daily energy expenditure for most people. Knowing your BMR gives you a baseline from which to estimate your total calorie needs once you account for physical activity.
What is TDEE?
Total daily energy expenditure (TDEE) is the total number of kilocalories you burn in a day, accounting for your BMR plus the energy cost of all physical activity, including exercise, daily movement, and the thermic effect of food. TDEE is your maintenance calorie level: eating this amount keeps your weight stable. Eating below TDEE causes weight loss; eating above it causes weight gain.
Which BMR formula is used?
This calculator uses the Mifflin-St Jeor equation, published by MD Mifflin and colleagues in the Journal of the American Dietetic Association in 1990. Research has consistently found the Mifflin-St Jeor equation to be the most accurate predictive equation for resting metabolic rate in most populations, outperforming the older Harris-Benedict equation. It uses weight (kg), height (cm), age (years), and sex.
How much of a calorie deficit is needed to lose 0.5 kg per week?
One kilogram of body fat contains approximately 7,700 kilocalories of stored energy. To lose 0.5 kg per week, you need a deficit of roughly 3,850 kcal per week, which is approximately 550 kcal per day. This calculator displays TDEE minus 550 kcal as the target for losing 0.5 kg per week. This is a general estimate: actual weight loss varies with water retention, dietary composition, and individual metabolism.
Are these calorie targets suitable for everyone?
The Mifflin-St Jeor equation is validated for most healthy adults but may be less accurate for very muscular individuals (who have higher BMR), elderly people (who tend to have lower BMR), or those with metabolic conditions. The equation does not account for pregnancy, breastfeeding, illness, or medication effects. Use these figures as a starting point, then adjust based on actual weight changes over two to four weeks. Consult a registered dietitian or healthcare provider for personalised nutrition advice.
Official sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. J Am Diet Assoc. 1990;90(3):402-407.
- Dietary Guidelines for Americans 2020-2025: dietaryguidelines.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology. General information only, not medical or nutritional advice.