A TDEE calculator estimates your body’s daily caloric expenditure by combining resting energy needs with the additional energy expended through physical activity. By entering your sex, age, height, weight, and habitual activity level, the calculator determines your caloric needs for weight maintenance—that is, the number of calories required to keep your weight stable. It does this using the Mifflin-St Jeor formula, which is commonly used by nutrition professionals.
How the TDEE Calculator Works
TDEE stands for total daily energy expenditure. It is built in two stages: work out what your body burns doing nothing at all, then multiply that by how much you move.
BMR and TDEE Are Not the Same Number
Basal metabolism refers to the amount of energy the body consumes to maintain vital functions, such as breathing, blood circulation, brain activity, and temperature regulation. It represents a lower limit, not a target. For a 30-year-old man who is 170 cm tall and weighs 65 kg, this figure is 1,568 calories per day.
Total daily energy expenditure also includes all other activities: walking, working, exercising, and even digesting food. If a moderate activity coefficient is applied to that same person, the figure rises to 2,430. The difference between 1,568 and 2,430 simply represents the energy expended during a typical day.
What You Need to Enter
- Sex – the equation uses different constants for men and women.
- Age – metabolic rate decreases progressively with age.
- Height – in centimeters.
- Weight – in kilograms.
- Activity level – amount of physical activity during a typical week.
The Mifflin-St Jeor Equation
This calculator uses the Mifflin-St Jeor equation, published in 1990 and now the formula most dietitians reach for. It replaced the older Harris-Benedict equation, which dates from 1919 and tends to overestimate for modern populations.
For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
The only difference between the two is the final constant, which reflects average differences in body composition. Running the male version for a 30-year-old at 170 cm and 65 kg gives 1,568 calories — the calculator’s default.
Activity Level Multipliers
Once the basal metabolic rate (BMR) is determined, the calculator multiplies it by a coefficient reflecting your activity level. The standard multipliers are presented below, shown against the calculator’s default BMR of 1,568 calories.
| Activity level | Multiplier | Daily calories |
|---|---|---|
| Sedentary — little or no exercise | 1.2 | 1,881 |
| Light — exercise 1–3 days/week | 1.375 | 2,155 |
| Moderate — exercise 3–5 days/week | 1.55 | 2,430 |
| Active — exercise 6–7 days/week | 1.725 | 2,704 |
| Very active — hard exercise + physical job | 1.9 | 2,978 |
The difference between the two extremes of this table is approximately 1,100 calories per day; precisely for this reason, activity level is the parameter most people get wrong. Most tend to overestimate it. A person who works in an office and trains three times a week is considered “moderate,” not “active.”
What the Weight Change Figures Mean
Below the main result, the calculator displays other values. These simply represent your maintenance calorie intake, adjusted up or down: a difference of approximately 275 calories per day corresponds to a weight change of a quarter of a kilogram per week, while 550 calories corresponds to half a kilogram.
These figures are purely theoretical and do not constitute recommendations. The calculator’s note summarizes the situation well: since metabolism varies from person to person, these values should be viewed as a starting point rather than a strict target. Anyone considering a significant change to their diet should consult a doctor or a qualified nutritionist rather than relying solely on a website.
How Accurate Is a TDEE Calculator?
The Mifflin-St Jeor formula is accurate to within approximately 10% for most people—a remarkable feat for a formula requiring only four input parameters. A systematic review published in the Journal of the American Dietetic Association found it more likely than the alternatives to land within that margin. Even among two individuals with the same height, weight, age, and sex, daily caloric needs can vary by several hundred calories; this is due to factors such as muscle mass, thyroid function, and genetics, none of which are accounted for by the equation.
The activity factor introduces more uncertainty than the equation itself. Consequently, the calculated value should be viewed as an initial estimate—to be adjusted over the weeks based on actual progress—rather than an exact figure to be relied upon down to the last calorie.
Frequently Asked Questions
What is TDEE?
TDEE (Total Daily Energy Expenditure) refers to your total daily energy output—that is, the number of calories your body burns throughout the day, including during periods of rest, movement, exercise, and digestion. It represents your caloric maintenance needs, or in other words, the amount of calories required to keep your weight generally stable.
What is the difference between BMR and TDEE?
BMR represents the amount of energy your body expends at complete rest. TDEE is calculated by multiplying BMR by an activity factor; therefore, it is always the higher of the two values. Using the calculator’s default settings, the difference is 1,568 versus 2,430.
How do you calculate TDEE?
Calculate your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor formula, then multiply it by an activity factor between 1.2 and 1.9. The calculator above performs both steps automatically once you enter your data.
Which activity level should you choose?
Choose the level that reflects a typical week, not your best week. An office job combined with three gym sessions is considered moderate. “Active” equates to training six or seven days a week, while “very active” usually involves hard exercise combined with physical labor.
Is the Mifflin-St Jeor formula better than the Harris-Benedict formula?
In general, it is more accurate for the modern population, which is why it has largely superseded the Harris-Benedict formula in clinical practice. The older equation was based on a much smaller and less representative sample dating back to 1919.
Why does my TDEE vary?
It adapts to weight, age, and activity level. Weight loss lowers this value, as a smaller body requires less energy to function. It also decreases progressively with age. Finally, changes in training volume can influence it in either direction.
Related Calculators
- BMI Calculator — the height-and-weight screening number.
- Body Fat Calculator — estimates composition, which BMI cannot.
- Percentage Calculator — for working with percentages generally.
- Age Calculator — age is one of the four inputs here.
- Date Difference Calculator — track intervals between measurements.