Estimate how many calories you need to eat daily to maintain, lose, or gain weight based on your age, gender, height, weight, and activity level using the Mifflin-St Jeor equation.
A 35-year-old female, 165 cm (5'5"), 68 kg (150 lbs), works a desk job with minimal exercise (Activity: Sedentary).
BMR (Mifflin-St Jeor): (10 × 68) + (6.25 × 165) − (5 × 35) − 161 = 680 + 1031.25 − 175 − 161 = 1,375 kcal/day
TDEE: 1,375 × 1.2 (Sedentary) = 1,650 kcal/day
Calories to maintain: ~1,650 kcal/day
To lose weight, she could aim for ~1,150-1,400 kcal/day (500 kcal deficit = ~0.5 kg/week loss).
A 28-year-old male, 180 cm (5'11"), 78 kg (172 lbs), exercises 5 days per week (Activity: Moderately Active).
BMR (Mifflin-St Jeor): (10 × 78) + (6.25 × 180) − (5 × 28) + 5 = 780 + 1125 − 140 + 5 = 1,770 kcal/day
TDEE: 1,770 × 1.55 (Moderately Active) = 2,744 kcal/day
Calories to maintain: ~2,744 kcal/day
For muscle gain (surplus): ~3,244 kcal/day (+500 kcal surplus)
A moderate surplus of 300-500 kcal/day supports lean muscle growth with minimal fat gain.
A 62-year-old male, 175 cm (5'9"), 92 kg (203 lbs), walks 3 times per week (Activity: Lightly Active).
BMR (Mifflin-St Jeor): (10 × 92) + (6.25 × 175) − (5 × 62) + 5 = 920 + 1093.75 − 310 + 5 = 1,709 kcal/day
TDEE: 1,709 × 1.375 (Lightly Active) = 2,350 kcal/day
Calories to maintain: ~2,350 kcal/day
For weight loss (deficit): ~1,850 kcal/day (−500 kcal deficit)
A 500 kcal daily deficit typically results in ~0.5 kg (1 lb) of fat loss per week. Always consult a doctor before starting any weight loss plan.
A 24-year-old female marathon runner, 168 cm (5'6"), 58 kg (128 lbs), trains daily (Activity: Very Active).
BMR (Mifflin-St Jeor): (10 × 58) + (6.25 × 168) − (5 × 24) − 161 = 580 + 1050 − 120 − 161 = 1,349 kcal/day
TDEE: 1,349 × 1.725 (Very Active) = 2,327 kcal/day
Calories to maintain: ~2,327 kcal/day
Endurance athletes need significantly more calories to fuel performance and recovery. Inadequate intake can lead to RED-S (Relative Energy Deficiency in Sport).
Your daily calorie needs are determined by your Basal Metabolic Rate (BMR) — the number of calories your body burns at complete rest — multiplied by an activity factor that accounts for your lifestyle and exercise habits. This gives you your Total Daily Energy Expenditure (TDEE), which is the number of calories you need to maintain your current weight.
Our calculator uses the Mifflin-St Jeor equation, which is widely regarded as the most accurate BMR formula for the general population. It was developed by MD Mifflin and ST St Jeor and validated in numerous studies. It differs for males and females because of differences in body composition and metabolism.
Once your BMR is calculated, it is multiplied by an activity factor that best describes your typical weekly physical activity level:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.200 | Little or no exercise, desk job |
| Lightly Active | 1.375 | Light exercise 1-3 days/week |
| Moderately Active | 1.550 | Moderate exercise 3-5 days/week |
| Very Active | 1.725 | Hard exercise 6-7 days/week |
| Extra Active | 1.900 | Very hard daily exercise + physical job |
These calculations provide scientifically validated estimates. Individual metabolism varies based on genetics, muscle mass, hormone levels, and other factors.
Recalculate your calorie needs whenever your weight changes by 5-10 kg (10-20 lbs), or if your activity level changes significantly.
Calorie quantity matters, but food quality matters too. Prioritize whole foods, adequate protein, fiber, and essential nutrients.
For medical conditions, pregnancy, eating disorders, or significant weight change goals, consult a registered dietitian or healthcare provider.
While this calculator uses the Mifflin-St Jeor equation (recommended by the Academy of Nutrition and Dietetics), other validated formulas exist:
Daily calorie intake refers to the total number of calories you consume through food and beverages in a 24-hour period. Your ideal calorie intake depends on multiple factors including your age, gender, height, weight, body composition, activity level, and overall health goals. Understanding your personal calorie needs is the foundation of effective weight management — whether your goal is to maintain your current weight, lose body fat, build muscle mass, or improve athletic performance.
The energy balance equation is simple in theory: if you consume more calories than you burn (a calorie surplus), you gain weight; if you consume fewer than you burn (a calorie deficit), you lose weight; and if intake equals expenditure (energy balance), your weight stays stable. However, individual metabolism is influenced by many factors including genetics, hormones, gut microbiome, muscle mass, sleep quality, stress levels, and even the thermic effect of food (TEF) — the energy required to digest and process what you eat.
Basal Metabolic Rate (BMR) is the minimum number of calories your body needs to perform basic life-sustaining functions such as breathing, circulating blood, regulating body temperature, and supporting brain and nervous system activity — essentially, the calories you'd burn if you stayed in bed all day. BMR accounts for approximately 60-75% of your total daily calorie expenditure, making it the single largest component of your energy budget.
Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a day, including BMR plus the energy used for physical activity (exercise and non-exercise activity thermogenesis or NEAT) and the thermic effect of food. TDEE is what you need to calculate to determine your maintenance calories — the amount you can eat without gaining or losing weight.
Understanding your personalized calorie intake requirements offers several important benefits for your health and wellness journey:
Know exactly how many calories to eat for weight loss, maintenance, or gain. Eliminate guesswork and set realistic, data-driven goals.
Eating the right amount of calories ensures you have enough energy for daily activities, exercise, work, and cognitive function.
Avoid extremes — too few calories can slow metabolism and cause muscle loss, while too many can lead to unwanted fat gain and metabolic issues.
Fine-tune your intake to support fat loss while preserving muscle, or to fuel muscle growth with minimal fat gain during bulking phases.
⚠️ Important Health Disclaimer: This Calorie Intake Calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Calorie needs vary significantly between individuals based on genetics, medical conditions, medications, and other factors. Pregnant or breastfeeding women, individuals with eating disorders, people with metabolic conditions (diabetes, thyroid disorders), and those on specific medications should consult a healthcare provider or registered dietitian before making significant changes to their calorie intake.