TDEE vs BMR: What's the Difference?

BMR and TDEE are the two numbers behind every calorie calculator, and they get mixed up constantly. They are related, one built from the other, but they answer different questions, and using the wrong one is a common way to end up eating far too little. Here is the plain-language difference, how each is calculated, and which number you should plan your diet around.

The short version: BMR is what your body burns doing nothing; TDEE is what it burns living your actual life. If you just want your number, our TDEE and macro calculator gives you both, but it is worth understanding what each one means so you use the right one.

What BMR is

BMR, basal metabolic rate, is the energy your body uses at complete rest to keep you alive: breathing, circulating blood, keeping organs running, maintaining body temperature. It is measured in a very specific state (awake, fasted, lying still in a comfortable room), which is why in everyday use people also refer to RMR (resting metabolic rate), a slightly looser, slightly higher version measured under less strict conditions. For practical purposes the two are close enough to treat as the same idea.

BMR is the biggest single chunk of your daily burn. The National Academies’ Dietary Reference Intakes put resting energy expenditure at roughly 60–70% of total energy expenditure. Everything else, moving and exercising and digesting, is stacked on top.

BMR is the calories your body burns at complete rest just to stay alive; TDEE is BMR plus everything else you do in a day.

What TDEE is

TDEE, total daily energy expenditure, is all the calories you burn in 24 hours. It is your BMR plus three other components:

• Physical activity, which the National Academies note can range from about 15% of total expenditure in a sedentary person up to 50% in a very active one. This splits into deliberate exercise and NEAT (non-exercise activity thermogenesis: walking, fidgeting, daily movement).
• The thermic effect of food: the energy spent digesting and processing meals, about 10% of daily expenditure.

Because TDEE includes everything and BMR includes only rest, TDEE is always larger than BMR. How much larger depends entirely on how active you are.

Term	What it measures	Rough share of the day
BMR / RMR	Calories at complete rest	~60–70% of TDEE
Physical activity	Exercise + daily movement (NEAT)	~15–50% of TDEE
Thermic effect of food	Digesting meals	~10% of TDEE
TDEE	The sum of all of the above	100%

How each is calculated

BMR is usually estimated first, then TDEE is built from it.

Step 1: Estimate BMR. The most widely used formula is Mifflin-St Jeor (weight in kg, height in cm, age in years):

• Men: BMR = (10 × weight) + (6.25 × height) − (5 × age) + 5
• Women: BMR = (10 × weight) + (6.25 × height) − (5 × age) − 161

Step 2: Multiply by an activity factor to get TDEE. The standard multipliers are:

Activity level	Multiplier
Sedentary (little/no exercise)	1.2
Lightly active (1–3 days/week)	1.375
Moderately active (3–5 days/week)	1.55
Very active (6–7 days/week)	1.725
Extra active (physical job + training)	1.9

So a woman with a BMR of 1,400 who trains a few times a week (×1.55) has a TDEE of about 2,170. Notice the gap: her TDEE is over 750 calories a day higher than her BMR. That gap is exactly why the distinction matters.

Which number should you use?

For almost every practical weight goal, use TDEE, not BMR. TDEE is your maintenance: the intake that keeps your weight stable. To lose weight you eat below TDEE; to gain you eat above it.

BMR is a reference point, not a target. Eating at your BMR means eating as if you spend the entire day motionless, which nobody does, so it almost always leaves you well under-fueled, which backfires through fatigue, muscle loss, and poor adherence. If you take one rule from this article: your calorie target is a percentage off your TDEE, and you can find both figures with the TDEE and macro calculator.

How accurate are these numbers?

Treat any calculated figure as an educated estimate, not a measurement. According to the Academy of Nutrition and Dietetics’ review, the Mifflin-St Jeor equation predicts resting metabolic rate within 10% of the measured value in about 70% of obese individuals, which is good for a formula, but it still means a meaningful share of people land outside that band. The activity multiplier adds more uncertainty, since self-rated activity is notoriously optimistic.

The practical fix is to use the calculated TDEE as a starting point, then adjust based on real results: if you eat at your estimated maintenance for two to three weeks and your weight drifts, your true TDEE is different from the estimate, and you nudge intake accordingly.

Where this matters on a GLP-1

If you are losing weight on a GLP-1, both numbers move as you get smaller: a lighter body has a lower BMR and therefore a lower TDEE. And how you spend your day still counts: keeping activity up preserves the larger, adjustable part of your TDEE and helps protect muscle, which is why GLP-1s and exercise are a better-together story. Recalculating both figures as your weight changes keeps your targets honest.

The takeaway

BMR is your at-rest burn; TDEE is your whole-day burn, and it is always the bigger of the two because it adds activity and digestion on top. Calculate BMR first, multiply by an activity factor to get TDEE, and plan your diet around TDEE, not BMR, which is too low to eat at. Every number here is an estimate, so verify it against real-world results and re-run it as your body changes. Get both figures fast with the TDEE and macro calculator.

This is educational information, not medical advice. Consult a clinician or registered dietitian before making significant dietary changes.

Sources

• Academy of Nutrition and Dietetics, Evidence Analysis Library — Determination of Resting Metabolic Rate
• National Academies, Dietary Reference Intakes for Energy — Factors Affecting Energy Expenditure (NCBI Bookshelf)