Calorie Calculator
Estimate the number of calories you need to consume each day to maintain, lose, or gain weight based on your activity level and body composition.
Understanding Calories and BMR
The Calorie Calculator is based on several well-established equations used to estimate your daily caloric needs. The results are based on estimated averages and provide a starting point for understanding your energy requirements.
Basal Metabolic Rate (BMR) represents the amount of energy your body expends per day at rest - essentially the calories needed to maintain basic bodily functions like breathing, circulation, and cell production. Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor that accounts for your daily physical activity level.
BMR Calculation Formulas
This calculator uses three different equations, each with its own strengths:
Mifflin-St Jeor Equation
Introduced in 1990, this equation is considered the most accurate for calculating BMR for the general population. It has been shown to be more accurate than the revised Harris-Benedict Equation.
Revised Harris-Benedict Equation
One of the earliest equations used to calculate BMR, originally developed in 1919 and revised in 1984 to improve accuracy. It was widely used until the introduction of the Mifflin-St Jeor Equation.
Katch-McArdle Formula
This formula is slightly different in that it calculates Resting Daily Energy Expenditure (RDEE), which takes lean body mass into account. This can be more accurate for people who are leaner and know their body fat percentage, as it accounts for muscle mass differences.
Activity Level Multipliers
Your TDEE is calculated by multiplying your BMR by an activity factor that reflects your typical exercise level:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Little or no exercise |
| Light | 1.375 | Exercise 1-3 times/week |
| Moderate | 1.55 | Exercise 4-5 times/week |
| Active | 1.725 | Daily exercise or intense exercise 3-4 times/week |
| Very Active | 1.9 | Intense exercise 6-7 times/week |
| Extra Active | 1.95 | Very intense exercise daily, or physical job |
Weight Loss Guidelines
The general principle of weight loss is that 1 pound (approximately 0.45 kg) equates to about 3,500 calories. To lose 1 pound per week, you would need to create a calorie deficit of approximately 500 calories per day (500 calories × 7 days = 3,500 calories).
Important Safety Note: It is inadvisable to lower calorie intake by more than 1,000 calories per day, as losing more than 2 pounds per week can be unhealthy and may reduce metabolism. Excessive weight loss can also be due to dehydration, which is unhealthy. Harvard Health Publications suggests women get at least 1,200 calories and men get at least 1,500 calories a day unless supervised by doctors.
Remember that proper diet and exercise is largely accepted as the best way to lose weight sustainably. Losing more than 2 pounds a week will likely involve muscle loss, which in turn lowers BMR, since more muscle mass results in higher BMR. It's important to maintain a balanced diet that supports your metabolic processes and provides essential nutrients.
How Many Calories Do You Need?
The number of calories your body needs depends on many factors including age, weight, height, sex, levels of physical activity, and overall general health. Though it differs depending on age and activity level, adult males generally require 2,000-3,000 calories per day to maintain weight while adult females need around 1,600-2,400 calories per day according to the U.S Department of Health.
The body does not require many calories to simply survive. However, consuming too few calories results in the body functioning poorly, since it will only use calories for functions essential to survival, and ignore those necessary for general health and well-being.