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Calorie Calculator

Calculate your daily calorie needs based on your activity level and weight goal.

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How to Use the Calorie Calculator

  1. Select your preferred unit system: US or Metric.
  2. Enter your age (18–80), select sex, and input height and weight. For adults 18 and older.
  3. Choose your activity level from the dropdown — this determines your maintenance calorie estimate.
  4. Select a goal: Maintain, Lose, or Gain weight. For loss/gain, choose a weekly rate.
  5. Open Advanced Settings to select a BMR formula if desired.
  6. Click Calculate to see your maintenance calories, goal calories, and a suggested macro split.

What is a Calorie?

A kilocalorie (kcal), commonly called a calorie in nutrition, is a unit of energy. It represents the amount of energy needed to raise the temperature of one kilogram of water by one degree Celsius. In nutrition, calories refer to the energy people get from the food and drink they consume, and the energy they use in physical activity.

Your body needs a baseline amount of energy each day just to keep your heart beating, lungs breathing, and cells functioning. This baseline, combined with your physical activity level, determines how many calories you need daily to maintain, lose, or gain weight.

A calorie deficit can lead to weight loss, but the amount and rate of weight change vary between individuals. The traditional 3,500-calorie-per-pound rule is a rough estimate and does not fully account for changes in metabolism and energy expenditure over time.

Factors That Influence Calorie Needs

Several factors determine how many calories your body requires each day.

  • •Age: Calorie needs often change with age due to changes in body composition, activity, and energy expenditure.
  • •Body composition: More muscle mass increases daily calorie expenditure.
  • •Activity level: Physical exercise is the most variable factor in daily energy expenditure.
  • •Sex: Calorie needs vary partly because average body composition and energy expenditure differ between males and females.
  • •Height and weight: Larger bodies require more energy to maintain basic functions.
  • •Weight goals: Losing or gaining weight requires adjusting calorie intake above or below maintenance.

Frequently Asked Questions

How many calories do I need per day?
Calorie needs vary considerably with age, body size, sex, and activity level. Broad population estimates often fall around 2,000–3,000 calories/day for men and 1,600–2,400 for women, but individual needs can be outside these ranges. Use this calculator for a personalized estimate.
Is it safe to eat 1,200 calories a day?
Calorie needs vary by age, sex, body size, activity level, and health status. Very-low-calorie diets may not provide enough energy or nutrients for some people and should be undertaken with appropriate medical or dietary supervision. If your calculated target is unusually low, consult a healthcare professional rather than using a generic calorie minimum.
How many calories should I eat to lose weight?
A moderate calorie deficit can support gradual weight loss, but the amount and rate of weight change vary between individuals. A deficit of around 500 calories/day is sometimes used as a starting point, but actual results depend on factors such as body size, activity, and metabolic adaptation. A gradual rate of around 1–2 pounds per week is commonly used in structured weight-loss programs, but an appropriate rate depends on the individual. Faster weight loss may require professional supervision.
Does exercise increase calorie needs?
Yes. Physical activity increases your total daily energy expenditure. The more active you are, the more calories your body needs. This is reflected in the activity level selection of this calculator.
How often should I recalculate?
Recalculate when your weight, activity level, or lifestyle changes meaningfully. You can also review your estimate periodically as your circumstances change.

References

1. Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990; 51: 241-247.

2. Hall KD, Heymsfield SB, Kemnitz JW, et al. Energy balance and its components: implications for body weight regulation. Am J Clin Nutr 2012; 95: 989-994.

This calorie calculator is for informational purposes only. It provides estimates based on published equations. It is intended for non-pregnant, non-breastfeeding adults. For personalized nutrition or medical advice, consult a qualified healthcare professional.

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