BMR, TDEE and calories burned: how to add them up without double counting

Basal metabolic rate, daily energy expenditure, calories burned on a walk: all three numbers are in kilocalories, which makes it tempting to add them together. That is exactly where most mistakes start. Each one answers a different question, and two of them already contain part of the others.

Three numbers, three questions

Basal metabolic rate (BMR) answers “how much energy does my body use at complete rest?”. Breathing, circulation, body temperature, organ function: it is the foundation of your day. It can be measured in a lab, but it is usually estimated with an equation such as Mifflin-St Jeor (1990), from weight, height, age and sex. The BMR calculator compares that equation with two others. According to the FAO/WHO/UNU report on human energy requirements, BMR makes up about 45 to 70% of an adult’s total expenditure.

Total daily energy expenditure (TDEE) answers “how much energy does my whole day cost?”. It adds digestion to your BMR, which Westerterp puts at 5 to 15% of daily expenditure, plus all your movement: commuting, work, chores and your usual workouts. In practice, the TDEE calculator multiplies your BMR by an activity factor, from 1.2 for a sedentary life to 1.9 for hard daily training.

Calories burned in a workout answer “how much did this particular activity cost?”. The calories burned calculator multiplies the activity’s MET value from the 2024 Compendium of Physical Activities by your weight and the time spent. It shows two results: total calories, which include the energy you would have used sitting down, and additional calories above rest, which leave that resting share out.

Two ways to count your exercise twice

Mistake one: an “active” activity level plus your workouts. If you pick “Lightly active” in the TDEE calculator because you walk three times a week, those walks are already in the result. Adding the calories of each walk on top counts them twice.

Mistake two: adding a workout’s total calories. During a 45-minute walk, your BMR keeps running, and it is already counted in your TDEE. Adding the workout’s total calories counts those 45 minutes of rest a second time. Add the additional calories, never the total.

A worked example

Take a 35-year-old woman, 5 ft 5 in (165 cm) and 154 lb (70 kg), with a desk job and three 45-minute brisk walks a week.

Step	Calculation	Result
BMR (Mifflin-St Jeor)	10 × 70 + 6.25 × 165 − 5 × 35 − 161	1,395 kcal/day
TDEE “Sedentary”	1,395 × 1.2	1,674 kcal/day
TDEE “Lightly active”	1,395 × 1.375	1,918 kcal/day
Brisk walk, 45 min (4.8 METs): total calories	4.8 × 70 × 0.75	252 kcal
Same walk: additional calories	(4.8 − 1) × 70 × 0.75	200 kcal

Two methods are correct:

• Method A, overall activity level: use 1,918 kcal a day, every day, and add nothing on walking days;
• Method B, workout by workout: use 1,674 kcal on rest days and 1,674 + 200 = 1,874 kcal on walking days, about 1,760 kcal a day on average over the week.

Two are wrong: 1,918 + 200 = 2,118 kcal counts the walks twice, and 1,674 + 252 = 1,926 kcal counts the 45 minutes of rest twice.

Methods A and B don’t land on the same number, and that is expected: the 1.375 factor describes a typical week, which also covers standing and moving around more. The gap of about 160 kcal shows how precise these estimates really are.

Which method should you use?

Method A suits a week that looks the same from one week to the next: same job, same workouts. You choose the activity level that describes it once, and the number stays steady.

Method B suits workouts that vary a lot from week to week, or when you want to compare their effect. Start from “Sedentary” and add each workout’s additional calories from the calories burned calculator.

Never mix the two.

Estimates, not measurements

Every step relies on averages. BMR equations miss the lab measurement by different amounts from one person to the next. Activity factors from 1.2 to 1.9 are conventional multipliers; the FAO/WHO/UNU report actually places a sedentary or lightly active lifestyle at 1.40 to 1.69 times BMR, above the usual 1.2. And a MET value describes a typical activity, not your actual effort; the Compendium authors point out that it does not reflect a given person’s precise expenditure.

If you are working toward a weight goal, treat these numbers as a starting point, then compare them with your weight trend over several weeks instead of adjusting what you eat day by day. These calculations are for information and do not replace advice from a health professional.