TDEE Calculator

TDEE stands for total daily energy expenditure — an estimate of the calories your body uses in an average day. It is also called your maintenance calories: if your food intake matches TDEE, body weight tends to stay roughly stable over time. This calculator builds that number from the Mifflin-St Jeor equation for resting metabolism and a five-step activity factor, then adds two practical targets: a mild 10% deficit and a mild 10% surplus.

This is an educational estimate, not a prescription. Calories in, calories out is real, but the numbers on both sides are approximations, and the calculators that produce them are only as good as the assumptions behind them.

What the calculator does

Enter age, sex, height in centimeters, and weight in kilograms, then choose an activity level. The tool computes:

• BMR — basal metabolic rate from Mifflin-St Jeor, the resting-energy part of your day (breathing, circulation, temperature regulation, cellular work).
• Maintenance calories (TDEE) — BMR multiplied by your activity factor.
• Mild deficit (10%) — a gently reduced target, useful as a starting point for weight loss planning rather than an aggressive cut.
• Mild surplus (10%) — a gently raised target, often used when trying to gain weight or support hard training.

The defaults (male, 30, 175 cm, 70 kg, moderate) immediately return about 2,556 kcal/day so you can see how the tool behaves before changing anything.

How it works

The Mifflin-St Jeor equation was developed from a study of 498 healthy adults and is a widely used predictor of resting energy expenditure. It starts from a shared base built from weight, height, and age:

$\text{base} = 10 \times \text{weight kg} + 6.25 \times \text{height cm} - 5 \times \text{age yr}$

The sex constant is then applied:

$\text{BMR (male)} = \text{base} + 5$

$\text{BMR (female)} = \text{base} - 161$

TDEE adds activity with a standard set of multipliers:

$\text{TDEE} = \text{BMR} \times \text{activity factor}$

The mild targets are simple percentages of TDEE:

$\text{mild deficit} = \text{TDEE} \times 0.9$

$\text{mild surplus} = \text{TDEE} \times 1.1$

All calorie readouts are rounded to whole calories per day.

Worked example

Take the defaults: male, age 30, 175 cm, 70 kg, moderate activity. The Mifflin base is:

$10 \times 70 + 6.25 \times 175 - 5 \times 30 = 700 + 1{,}093.75 - 150 = 1{,}643.75$

Adding 5 for a male gives a BMR of 1,648.75, displayed as 1,649 kcal/day. Moderate activity uses 1.55:

$\text{TDEE} = 1{,}648.75 \times 1.55 = 2{,}555.5625$

The displayed maintenance figure is 2,556 kcal/day. The 10% targets follow:

$\text{mild deficit} = 2{,}555.5625 \times 0.9 = 2{,}300.00625 \rightarrow \textbf{2,300 kcal/day}$

$\text{mild surplus} = 2{,}555.5625 \times 1.1 = 2{,}811.11875 \rightarrow \textbf{2,811 kcal/day}$

So the result shows maintenance 2,556, with a mild deficit of 2,300 and a mild surplus of 2,811 kcal/day.

Interpreting the estimate

A TDEE estimate is a starting point, not a measurement. The Mifflin-St Jeor equation predicts resting expenditure from population data; it cannot see your muscle mass, thyroid status, medications, illness, or genetic variance, all of which shift real energy use. The activity factor is a bigger source of uncertainty: most people are not sure which bucket they belong in, and a person with an active job plus training differs from someone who sits all day and trains once.

A practical check is the weight-trend test. If you log intake honestly for a few weeks and body weight stays flat, your real maintenance is close to your logged intake — regardless of what any formula says. Use the formula to choose a starting point, then adjust from observed trends rather than re-running the calculator forever.

Related tools on this site cover nearby questions: the BMR calculator reports the resting estimate with a Harris-Benedict comparison, the resting energy expenditure calculator shows the equation result without any activity adjustment, the protein calculator turns calorie targets into a protein intake range, and the body-fat calculator adds a body-composition view that calorie formulas ignore.

Limits of the estimate

• Population math, not personal physiology. The equation averages across people; individual variance can be hundreds of calories per day.
• Activity factors are crude. “Moderate” means different things to different people, and the factor cannot tell an office day from a marathon taper.
• A 10% cut is mild on purpose. Larger deficits are beyond this tool’s scope and come with different risks, especially if protein intake and training are not managed.
• Not for children or medical use. The equation was built from adult data; pregnancy, illness, eating disorders, and metabolic conditions all call for individualized professional guidance instead.

Tips for using the result

• Pick the activity level that describes your typical weeks, not your best week — aspiration inflates the estimate.
• Weigh and log food before trusting the targets; intake tracking errors are routinely larger than the 10% margins shown here.
• Pair a deficit with the protein calculator so the reduced calories still contain enough protein for lean mass.
• Re-check after meaningful changes: a 5 kg weight shift or a new training program changes the inputs the formula depends on.

Common pitfalls

• Choosing an activity factor for the person you want to be, then wondering why weight does not move as predicted.
• Treating BMR as a calorie target. BMR is the resting floor; most people’s real needs are noticeably higher, which is why TDEE exists.
• Comparing numbers across calculators without checking the equation and factors — different sites use Harris-Benedict, Katch-McArdle, or dynamic models, and the outputs can differ by hundreds of calories.
• Re-entering goal weight instead of current weight. The formula uses current weight; if you want a target-weight estimate, recompute when weight changes.

Sources

• Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO, A new predictive equation for resting energy expenditure in healthy individuals, American Journal of Clinical Nutrition 1990;51(2):241–247 — source of the Mifflin-St Jeor equation used for BMR.
• NIDDK, Body Weight Planner — research-based explanation of energy balance and how intake, activity, and weight change interact.
• CDC, Physical Activity Guidelines for Adults — public-health context for adult activity levels behind the activity factors.