How to Calculate Your TDEE

Overview

Total daily energy expenditure, or TDEE, is the total number of calories you burn in a day.

It is calculated in two steps: work out your basal metabolic rate, the energy you would use lying still all day, then multiply it by an activity factor.

Quick Answer

To calculate TDEE, first find your basal metabolic rate using the Mifflin St Jeor equation, then multiply it by an activity factor between 1.2 for sedentary and 1.9 for very active. The result estimates your maintenance calories.

Key Points

Two steps: BMR, then an activity multiplier.
Mifflin St Jeor is the most accurate general equation.
The activity multiplier is where most of the error comes from.
Expect the result to be within about 10 percent, not exact.
Correct it with two weeks of real weight data.

Step one: basal metabolic rate

The Mifflin St Jeor equation, using kilograms and centimetres:

Men: BMR = (10 x weight) + (6.25 x height) - (5 x age) + 5

Women: BMR = (10 x weight) + (6.25 x height) - (5 x age) - 161

Worked example, a 30 year old woman, 65kg, 168cm:

Term	Calculation	Value
Weight	10 x 65	650
Height	6.25 x 168	1050
Age	5 x 30	minus 150
Constant	Female	minus 161
BMR		1389

Step two: activity multiplier

Multiplier	Description	Realistically means
1.2	Sedentary	Desk job, no training, under 5,000 steps
1.375	Lightly active	Desk job, 1 to 3 sessions weekly
1.55	Moderately active	3 to 5 sessions weekly, decent daily movement
1.725	Very active	6 to 7 sessions, or an active job
1.9	Extremely active	Physical job plus daily training

This is where estimates go wrong. Most people select a level above their actual one, because training three times a week feels active even when the other 165 hours of the week are spent sitting.

Continuing the example, at 1.375: 1389 x 1.375 = roughly 1910 calories per day.

The quick alternative

If you would rather skip the arithmetic:

Activity level	Calories per kg bodyweight
Sedentary	28 to 30
Lightly active	30 to 33
Moderately active	33 to 37
Very active	38 plus

For a 65kg lightly active person that gives 1950 to 2145, in the same region as the equation. The agreement is reassuring but neither is precise.

Correcting the estimate

The equation predicts a population average. You are not a population average.

1. Eat at your calculated TDEE for two weeks, tracking honestly.

2. Weigh yourself daily and take a seven day average.

3. If weight held steady, that intake is your real maintenance.

4. If it rose or fell, adjust by 150 to 200 calories and repeat.

After one or two cycles you have a measured number rather than a predicted one, and it will serve you far better.

Why calculators disagree

Different sites use different equations, some using the older Harris Benedict formula, and some apply body fat percentage adjustments. A spread of 300 to 400 calories between calculators for the same person is entirely normal.

The activity multiplier accounts for more of that spread than the equation does.

Common Mistakes

Mistake	Why it causes problems	Better approach
Choosing an inflated activity level	Overestimates maintenance considerably	Be conservative and adjust up
Adding exercise calories on top	The multiplier already includes them	Pick one method
Treating the result as exact	It is an estimate with real error	Test and correct
Recalculating every week	Adds noise	Recalculate after 5kg of change
Using a BMR figure as a calorie target	BMR is not TDEE	Always apply the multiplier

Frequently Asked Questions

Which BMR equation is most accurate?

Mifflin St Jeor is generally regarded as the most accurate for the general population. Katch McArdle can be better if you know your body fat percentage reliably.

Should I eat my BMR or my TDEE?

Neither is a target by itself. TDEE is your estimated maintenance; you set a target above or below it depending on your goal.

How often should I recalculate?

After a change in bodyweight of about 5kg, or a meaningful change in activity. Otherwise, adjust from weight data rather than recalculating.

Why is my actual maintenance different from the calculation?

Individual variation in metabolic rate and daily movement is substantial. The equation gives a population estimate; your body gives the real answer.