Calorie Intake Calculator
Enter your details and activity level to see how many calories you need each day to maintain your weight. Adjust the goal to get calorie targets for gradual or rapid weight loss, muscle gain, or anywhere in between. The result includes your Basal Metabolic Rate, TDEE, a macro split, a 7-day chart, and a plain-English interpretation of your numbers. Switch between metric and imperial units at the top.
Formula
Worked example
A 30-year-old male, 70 kg, 175 cm, moderately active: BMR = (10 x 70) + (6.25 x 175) - (5 x 30) + 5 = 700 + 1,093.75 - 150 + 5 = 1,648.75 kcal. TDEE = 1,648.75 x 1.55 = 2,555 kcal. To lose roughly 1 lb per week, the target is 2,555 - 500 = 2,055 kcal/day.
What is a calorie and why does your daily intake matter?
A calorie (kilocalorie, kcal) is the amount of energy needed to raise one kilogram of water by one degree Celsius. Your body uses this energy continuously, from keeping your heart beating and your brain active to fuelling every step you take. When you consistently eat more calories than you burn, the surplus is stored as body fat; when you eat fewer, stored fat is mobilized for fuel. Understanding your daily calorie need is therefore the foundation of any weight-management plan, whether the goal is loss, maintenance, or gain. This calculator estimates that number using the most thoroughly validated formula available for free-living adults.
How BMR and TDEE are calculated
Basal Metabolic Rate (BMR) is the energy your body needs at absolute rest, just to maintain basic organ function. This calculator uses the Mifflin-St Jeor equation, published in 1990 and consistently ranked as the most accurate BMR formula for the general adult population in systematic reviews. The formula is: BMR (male) = 10W + 6.25H - 5A + 5 and BMR (female) = 10W + 6.25H - 5A - 161, where W is weight in kg, H is height in cm, and A is age in years. Your Total Daily Energy Expenditure (TDEE) scales BMR upward by an activity factor that accounts for the calories you burn through deliberate exercise and everyday movement. A sedentary person multiplies by 1.2; someone training intensively every day multiplies by 1.9. The product is your maintenance calorie intake, i.e., the number of calories that would keep your weight stable over time.
Calorie targets for different goals
Once you have your TDEE, you can set a calorie target based on your goal. A deficit of 500 kcal per day produces a theoretical loss of roughly 0.5 kg (1 lb) per week, because stored body fat contains about 7,700 kcal per kilogram (3,500 kcal per pound). A 1,000 kcal deficit doubles that rate but is harder to sustain and carries a higher risk of muscle loss without adequate protein intake. On the surplus side, a 250-500 kcal excess paired with progressive resistance training supports muscle growth without excessive fat accumulation. Targets below 1,200 kcal/day are classified as very low calorie diets (VLCDs) and should only be followed under medical supervision, because they are difficult to make nutritionally adequate from food alone.
Macronutrient targets and why they matter alongside total calories
Total calories determine the direction of weight change, but macronutrient ratios influence body composition, satiety, and performance. This calculator uses a 40-30-30 split as a widely applicable starting point: 40% of calories from carbohydrates (4 kcal/g), 30% from protein (4 kcal/g), and 30% from fat (9 kcal/g). Protein is especially important during a deficit because it helps preserve lean muscle mass; most research supports 1.6-2.2 g per kg of body weight per day for active individuals. Carbohydrates are the primary fuel for high-intensity exercise, and dietary fat is essential for hormone production and fat-soluble vitamin absorption. Adjust these ratios to suit your dietary approach or health conditions, and consider consulting a registered dietitian if you have specific medical needs.
Activity level multipliers (Mifflin-St Jeor TDEE)
| Activity level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.20 | Desk work, minimal movement outside it |
| Light | 1.375 | 1-3 light workouts per week |
| Moderate | 1.55 | 4-5 moderate workouts per week |
| Active | 1.725 | Daily exercise or hard training most days |
| Very active | 1.90 | Physical job or two-a-day training |
Multiply your BMR by the factor below to estimate total daily calorie needs.
Frequently asked questions
What is the most accurate formula for calculating calorie needs?
The Mifflin-St Jeor equation, developed in 1990, is the most consistently accurate BMR formula for non-obese and obese adults in peer-reviewed systematic reviews. The Harris-Benedict equation (revised 1984) is also widely used but tends to overestimate slightly. Katch-McArdle is theoretically superior if you know your lean body mass, because it bypasses the sex constant, but body fat percentage is harder to measure accurately. For most people, Mifflin-St Jeor is the best starting point.
How many calories should I eat to lose weight?
Start by calculating your TDEE (maintenance calories) using your activity level. Subtract 500 kcal per day to target roughly 1 lb (0.45 kg) of loss per week. Subtract 250 kcal for a gentler 0.5 lb/week pace. Deficits greater than 1,000 kcal per day are not recommended without medical guidance, as they increase muscle loss risk and are nutritionally difficult to sustain. In practice, most people lose faster than theory predicts in the first week due to water loss, then settle closer to the expected rate.
Can I eat fewer than 1,200 calories a day?
Very low calorie diets (VLCDs), typically defined as below 800 kcal/day, and low-calorie diets below 1,200 kcal/day for women and 1,500 kcal/day for men require medical supervision. At these levels it becomes extremely difficult to meet vitamin and mineral requirements from food alone, and the risk of muscle loss, nutrient deficiency, and metabolic adaptation increases significantly. If your calculated goal falls below 1,200 kcal, speak with a doctor or registered dietitian before proceeding.
Why does the formula use biological sex rather than gender?
The Mifflin-St Jeor equation was derived from physiological measurements and uses biological sex because males and females differ in average lean body mass at a given height and weight. Men have, on average, more muscle and less body fat than women of the same size, and muscle burns more calories at rest. If your physiology differs from the binary option shown (for example, due to hormone therapy), use the option that most closely matches your current hormonal and body composition profile, or consult a dietitian for a personalized estimate.
How does activity level affect my calorie needs?
Activity multipliers range from 1.2 for a largely sedentary person to 1.9 for someone with a physical job and intensive daily training. The difference between sedentary and very active at the same BMR can be 600-900 kcal/day or more. This is why two people of the same height, weight, age, and sex can have very different maintenance calorie needs. When in doubt, err toward a lower multiplier: it is easier to add more calories if you are losing too quickly than to cut back if you are gaining.
What does TDEE mean?
TDEE stands for Total Daily Energy Expenditure: the total number of calories your body burns in 24 hours, including your resting metabolism, the thermic effect of digesting food (roughly 10% of intake), and all physical activity from formal workouts to simply standing or fidgeting. Eating at your TDEE maintains your current weight. Eating below it creates a deficit; eating above it creates a surplus.
How accurate is this calorie calculator?
Equations like Mifflin-St Jeor estimate calorie needs within about 10% for most people. Real TDEE varies based on gut microbiome, non-exercise activity thermogenesis (NEAT), hormonal factors, sleep quality, and other variables no formula can capture. Treat the result as a starting estimate. Track your weight and food intake for 2-3 weeks; if weight is changing faster or slower than expected, adjust your calorie target by 100-200 kcal and reassess.
Sources
- Mifflin MD et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition.
- National Academy of Medicine (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press.
- Frankenfield D et al. (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. Journal of the American Dietetic Association.