BMR and TDEE Explained: The Difference and How to Calculate Them
When you set your calories for a cut or a bulk, the first thing you want to know is how much energy your body burns each day. The two numbers that answer this are your BMR (basal metabolic rate) and your TDEE (total daily energy expenditure). This guide explains the difference between them and shows you how to work out your own numbers, formula included.
What is BMR (basal metabolic rate)?
BMR (Basal Metabolic Rate) is the energy your body burns at complete rest, just to stay alive — breathing, heartbeat, body temperature, and organ function. It is the single largest part of your daily burn, typically about 60–70% of the total.
How big your BMR is depends mainly on body size (especially lean/fat-free mass), age, and sex. Larger and more muscular people have a higher BMR, and it declines gradually with age.
What is TDEE (total daily energy expenditure)?
TDEE (Total Daily Energy Expenditure) is your BMR plus the energy you spend moving through your day — the total calories you burn in 24 hours. It is made up of the following parts.
| Component | What it covers | Rough share |
|---|---|---|
| BMR | Minimum energy to keep you alive at rest | ~60–70% |
| Physical activity (NEAT + exercise) | Chores, commuting, standing work, workouts | ~20–30% |
| Thermic effect of food (TEF) | Energy used to digest and absorb food | ~10% |
Calculating BMR: the Mifflin-St Jeor equation
Several formulas estimate BMR from height, weight, age, and sex. The one considered most accurate today is the Mifflin-St Jeor equation (1990), adopted by the Academy of Nutrition and Dietetics. Our TDEE Calculator uses it too.
- Men:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 - Women:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
For example, a 30-year-old man, 170cm, 65kg: 10×65 + 6.25×170 − 5×30 + 5 = 650 + 1062.5 − 150 + 5 ≈ 1568 kcal is his estimated BMR.
Calculating TDEE: multiply by an activity factor
Once you have BMR, multiply it by an activity factor that reflects how active you are: TDEE = BMR × activity factor. The commonly used factors are:
| Activity level | Typical of | Factor |
|---|---|---|
| Sedentary | Desk job, little or no exercise | ×1.2 |
| Light | Light exercise / walking 1–3 days a week | ×1.375 |
| Moderate | Training 3–5 days a week (most people) | ×1.55 |
| Heavy | Hard training almost daily | ×1.725 |
| Very heavy | Athlete, physical job, two-a-day training | ×1.9 |
If the person above (BMR 1568) is at "moderate" activity (×1.55), then 1568 × 1.55 ≈ 2430 kcal is his estimated TDEE. Choose the factor based not only on workouts but also on how much your job and daily life move you. If unsure, start around ×1.375–1.55.
How to use your TDEE
TDEE is the baseline for setting food intake. Adjust up or down from it depending on your goal.
- Fat loss: eat roughly 200–500 kcal below TDEE per day. Cutting too hard (especially below BMR) tends to cost muscle and cause rebound.
- Maintenance: eat around TDEE.
- Muscle gain: eat roughly 200–400 kcal above TDEE, kept gradual so you add less fat.
Once you set your calories, split them into protein, fat, and carbs with the PFC Calculator, and set protein using the protein intake guide. For how balance drives weight change, see the calorie-balance guide.
A caveat: these are estimates
The BMR and TDEE you get from a formula are statistical estimates. Real metabolism varies with muscle mass, body composition, hormones, and genetics, so two people of the same size can differ by hundreds of kcal.
Summary
BMR is the baseline you burn at rest; TDEE is that baseline plus activity — your real daily burn. The workflow: estimate BMR with Mifflin-St Jeor → multiply by an activity factor for TDEE → adjust intake for your goal → fine-tune from the weight trend. With this you can manage food by numbers instead of guesswork. Start by plugging your figures into the TDEE Calculator.
・Mifflin, M. D., St Jeor, S. T., et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 51(2), 241–247.
・Frankenfield, D., et al. (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. J Am Diet Assoc, 105(5), 775–789.
・Levine, J. A. (2004). Non-exercise activity thermogenesis (NEAT). Nutrition Reviews, 62, S82–S97.