If you have ever used a macro calculator and seen two different numbers pop out, BMR and TDEE, you are not alone in being confused about which one to eat to. Both represent how many calories your body burns, but they count different things. Getting this right matters because setting your calorie target from the wrong number leads to slow progress at best and muscle loss or weight gain at worst.
This guide explains what each number is, how to calculate both, and which one to use depending on your goal.
The Short Version
BMR (Basal Metabolic Rate) is the calories your body burns just keeping you alive at complete rest: breathing, pumping blood, maintaining body temperature, running your brain. For most adults this is 1,200 to 1,900 calories.
TDEE (Total Daily Energy Expenditure) is BMR plus everything else: walking to the kitchen, your job, exercise, even the calories burned digesting food. TDEE is always larger than BMR, usually by 25 to 80%.
You eat to your TDEE, not your BMR. Eating to BMR alone is a near-starvation diet for most active people.
How BMR Is Calculated
The most-validated formula is the Mifflin–St Jeor equation, published in the American Journal of Clinical Nutrition in 1990 and still the standard across dietetics and sports science.
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.
Worked example for a 35-year-old woman who is 5'6" (168 cm) and 145 lb (66 kg):
BMR = (10 × 66) + (6.25 × 168) − (5 × 35) − 161 BMR = 660 + 1,050 − 175 − 161 BMR = 1,374 calories per day.
If she did nothing but lie in bed for 24 hours, her body would still burn 1,374 calories keeping her alive.
Older formulas like Harris-Benedict (1919, updated 1984) tend to overestimate BMR by 5 to 10% in modern adults. Katch-McArdle is sometimes more accurate for very lean, muscular individuals because it uses lean body mass instead of total weight, but it requires you to know your body fat percentage.
What Makes Up BMR
About 60 to 70% of your total daily calorie burn comes from BMR, broken down roughly like this:
| System | % of BMR |
|---|---|
| Liver | 27% |
| Brain | 19% |
| Skeletal muscle | 18% |
| Kidneys | 10% |
| Heart | 7% |
| Other tissues | 19% |
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This is why having more muscle increases your BMR: muscle tissue is metabolically active even at rest. Adding 5 lb of muscle adds roughly 25 to 50 calories per day to BMR. Not huge, but it compounds.
How TDEE Is Calculated
TDEE = BMR × activity multiplier.
The standard activity multipliers:
| Activity level | Multiplier | Who it fits |
|---|---|---|
| Sedentary | 1.2 | Desk job, no exercise, low daily steps |
| Lightly active | 1.375 | Desk job with 1 to 3 light workouts per week |
| Moderately active | 1.55 | Active job or 3 to 5 workouts per week |
| Very active | 1.725 | Physical job or 6 to 7 workouts per week |
| Extra active | 1.9 | Physical job plus daily training |
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Back to our 35-year-old woman with BMR 1,374. If she works at a desk and does yoga twice a week, she is "lightly active":
TDEE = 1,374 × 1.375 = 1,889 calories per day.
That is her maintenance calories. Eating 1,889 calories daily keeps her weight stable.
What Makes Up TDEE (Beyond BMR)
The gap between BMR and TDEE is made up of four components:
NEAT (Non-Exercise Activity Thermogenesis). All the calories you burn from moving around outside of structured exercise: walking, fidgeting, standing, household tasks. NEAT varies enormously between individuals. Two people with the same BMR can differ by 600 to 800 calories per day based on NEAT alone.
EAT (Exercise Activity Thermogenesis). Calories burned during intentional workouts. A 30-minute moderate run burns about 300 calories. Weight training is typically 150 to 250 per hour.
TEF (Thermic Effect of Food). Calories burned digesting your food. Protein has the highest TEF at 20 to 30%. Carbs are 5 to 10%. Fat is 0 to 3%. TEF is roughly 10% of total intake on a mixed diet.
Adaptive thermogenesis. Your body's tendency to burn slightly more or less depending on whether you are in a surplus or deficit. This is why weight loss slows over time, not because the math changed, but because your body adapted.
Which Number Should You Eat To?
Almost always, you eat to your TDEE, not your BMR.
For weight loss: TDEE minus a 15 to 20% deficit. Our 1,889-TDEE example would eat 1,510 to 1,605 calories per day.
For maintenance: eat exactly at TDEE.
For muscle gain: TDEE plus 5 to 15% surplus. 1,980 to 2,170 calories per day for the same example.
Eating at your BMR directly is considered a starvation-level deficit for anyone beyond truly sedentary. Your body responds by reducing NEAT, slowing thyroid output, dropping muscle to conserve energy, and eventually stalling weight loss entirely. Very-low-calorie diets (800 to 1,200 calories) are medically supervised interventions for severe obesity, not casual weight loss strategies.
Why Calculated TDEE Is an Estimate, Not a Promise
Any TDEE you calculate is an estimate based on population averages. Real TDEE in a single individual can be off by 10 to 15% in either direction because of:
- Individual differences in NEAT (some people fidget, some do not)
- Muscle mass not captured in the weight-based formula
- Adaptive metabolism (slightly lower in chronic dieters, slightly higher in overfeeders)
- Measurement noise in self-reported activity level
Treat your calculated TDEE as a starting point. Eat at that level for 2 to 3 weeks, track weight weekly, and adjust by 100 to 200 calories based on what actually happens.
When BMR Alone Is Useful
BMR matters in a few specific contexts. It sets a floor: most nutrition professionals recommend not dropping weight-loss calories below about 1.1 × BMR for women or 1.2 × BMR for men, to protect muscle and thyroid function. It is also used for calculating protein targets in low-calorie medically-supervised diets. And tracking BMR over time can reveal whether metabolism has adapted downward after a prolonged diet.
For everyday calorie-and-macro planning, though, TDEE is the number that matters.
Quick Reference
Think of BMR as your car's idle fuel consumption when parked with the engine on. TDEE is what you actually use driving around all day. You fill the tank based on the driving, not the idle.
Run your own numbers in the DrinkDigits Macro Calculator, which gives you BMR, TDEE, and macro targets in one step. For the full weight-loss math including deficit and protein targets, see how to calculate macros for weight loss. For the basics of macronutrients, start with macros explained.
Sources & References
- Mifflin MD et al., Am J Clin Nutr (1990). Original Mifflin–St Jeor BMR equation.
- Levine JA, Best Pract Res Clin Endocrinol Metab (2002). NEAT and its effect on total energy expenditure.
- NIH Office of Dietary Supplements: Energy. Dietary reference intakes for energy.
- Academy of Nutrition and Dietetics. Registered dietitian guidance on metabolic calculations.
