Calorie Calculator - Free Online Calculator

How This Calorie Calculator Works

This calorie calculator estimates how many calories your body needs each day to maintain its current weight. It calculates two key values: your BMR (Basal Metabolic Rate) — the calories your body burns at complete rest just to keep you alive — and your TDEE (Total Daily Energy Expenditure) — your total daily calorie burn including physical activity.

Enter your age, gender, weight in kilograms, height in centimetres, and select your activity level. The calculator uses the Mifflin-St Jeor equation (widely regarded as the most accurate BMR formula) to compute your BMR, then multiplies it by an activity factor to give your maintenance calories. It also shows target calories for weight loss and weight gain.

All calculations happen locally in your browser. No data is stored or shared.

BMR and TDEE Formulas

This calculator uses the Mifflin-St Jeor equation (1990), recommended by the Academy of Nutrition and Dietetics:

Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Your TDEE is then calculated by multiplying BMR with an activity factor:

TDEE = BMR × Activity Factor

Sedentary (1.2) — Little or no exercise, desk job
Lightly Active (1.375) — Light exercise 1-3 days per week
Moderately Active (1.55) — Moderate exercise 3-5 days per week
Very Active (1.725) — Hard exercise 6-7 days per week

Example Calculation

Inputs:

Age: 30 years
Gender: Male
Weight: 75 kg
Height: 175 cm
Activity Level: Moderately Active

Step-by-step:

BMR = (10 × 75) + (6.25 × 175) − (5 × 30) + 5
BMR = 750 + 1,093.75 − 150 + 5 = 1,699 kcal/day
TDEE = 1,699 × 1.55 = 2,633 kcal/day

This means a 30-year-old male who exercises moderately needs about 2,633 calories per day to maintain his current weight. To lose weight, he would target ~2,133 kcal (500 deficit); to gain weight, ~3,133 kcal (500 surplus).

Understanding BMR vs TDEE

BMR and TDEE are related but measure different things. Understanding the difference is essential for setting accurate calorie targets:

BMR (Basal Metabolic Rate) — The calories your body burns at absolute rest: breathing, circulation, cell repair, brain function. This accounts for 60-75% of your total daily burn. You should generally never eat below your BMR for extended periods.
TDEE (Total Daily Energy Expenditure) — Your BMR plus all additional calorie burn from physical activity, walking, exercise, and the thermic effect of food (calories burned digesting meals). This is the number you should use for calorie planning.

For weight loss, create a moderate deficit below your TDEE (not your BMR). A deficit of 500 kcal/day below TDEE leads to approximately 0.5 kg (1 pound) of fat loss per week. For weight gain, eat 300-500 kcal above your TDEE while strength training to build lean muscle.

Choosing the Right Activity Level

The activity multiplier has a significant impact on your TDEE — selecting the wrong level can over- or under-estimate your needs by hundreds of calories. Here is how to choose accurately:

Sedentary (1.2) — You work a desk job and do not exercise. Daily steps are under 5,000. Most of your day is spent sitting.
Lightly Active (1.375) — You walk regularly (5,000-7,500 steps/day) or do light workouts like yoga, stretching, or casual walks 1-3 times per week.
Moderately Active (1.55) — You exercise at moderate intensity (jogging, cycling, swimming, gym workouts) 3-5 days per week, or have a physically active job like teaching or retail.
Very Active (1.725) — You train hard 6-7 days per week (running, weight training, sports) or have a physically demanding job like construction, farming, or manual labour.

When in doubt, choose one level lower than you think. It is better to slightly underestimate and adjust upward based on real results over 2-3 weeks.

Common Use Cases

Weight Loss Planning — Calculate your TDEE and subtract 500 calories to create a sustainable deficit that leads to steady fat loss of about 0.5 kg per week without extreme restriction.
Muscle Building (Bulking) — Determine your maintenance calories and add a 300-500 calorie surplus. Combined with progressive strength training, this supports lean muscle growth.
Maintaining Current Weight — Know your exact TDEE so you can eat the right amount to stay at your current weight, especially useful after reaching a goal weight.
Fitness and Nutrition Tracking — Use your TDEE as the baseline for macro splits (protein, carbs, fats) when following structured meal plans or tracking food intake.
Post-Diet Reverse Dieting — After a prolonged calorie deficit, gradually increase calories back toward your TDEE to restore metabolic rate without rapid weight regain.
Health Awareness — Understand how factors like age, weight, and activity level affect your energy needs, helping you make more informed dietary choices.

Frequently Asked Questions

How are daily calories calculated?

Daily calories are calculated by first determining your Basal Metabolic Rate (BMR) using factors like age, gender, weight, and height, then multiplying it by an activity factor to get your Total Daily Energy Expenditure (TDEE).

What is BMR?

BMR stands for Basal Metabolic Rate. It is the number of calories your body needs at complete rest to maintain basic life-sustaining functions such as breathing, circulation, and cell production. It typically accounts for 60-75% of total daily calorie expenditure.

What is TDEE?

TDEE stands for Total Daily Energy Expenditure. It represents the total number of calories you burn in a day, combining your BMR with calories burned through physical activity and the thermic effect of food.

How does activity level affect calorie needs?

Activity level significantly impacts calorie needs. A sedentary person may need 1,800 calories per day while a very active person of the same size might need 2,800 or more. The activity multiplier ranges from 1.2 for sedentary to 1.9 for extremely active individuals.

Should I eat below my TDEE to lose weight?

Yes, eating below your TDEE creates a caloric deficit which leads to weight loss. A moderate deficit of 500 calories per day typically results in about 0.5 kg (1 pound) of weight loss per week. However, it is important not to go too far below your BMR for sustained health.

Is the Mifflin-St Jeor formula accurate?

The Mifflin-St Jeor formula is considered one of the most accurate BMR estimation formulas available, typically within 10% of measured values for most people. It was developed in 1990 and is widely recommended by dietitians and health professionals.

How many calories for weight gain?

To gain weight, you need to eat above your TDEE. A surplus of 300-500 calories per day is commonly recommended for lean muscle gain. Larger surpluses lead to faster weight gain but may include more fat. Combining a calorie surplus with strength training promotes muscle growth.

Do calorie needs change with age?

Yes, calorie needs generally decrease with age as metabolism slows and muscle mass tends to decline. After age 30, BMR drops by roughly 1-2% per decade. Staying physically active and maintaining muscle mass through exercise can help offset this decline.

Important Notes

This calorie calculator uses the Mifflin-St Jeor equation, which estimates BMR within approximately 10% accuracy for most individuals. Actual calorie needs can vary based on genetics, body composition (muscle-to-fat ratio), hormonal factors, and medical conditions.

The calculator provides a starting point, not a prescription. Monitor your weight over 2-3 weeks and adjust intake by 100-200 calories if you are not seeing expected results. Factors like water retention, sleep quality, and stress can cause short-term weight fluctuations.

For specific dietary needs related to medical conditions (diabetes, thyroid disorders, eating disorders), consult a registered dietitian or healthcare provider rather than relying solely on calculator estimates.

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