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BMR vs. TDEE: What's the Difference and Which Should You Use?
Last updated: June 2026
When you start tracking calories, two acronyms appear constantly: BMR and TDEE. They're related but not interchangeable — and mixing them up is one of the most common reasons people set calorie targets that are too low, too high, or just wrong for their goals. Here's a precise breakdown of what each number means, how to calculate it, and which one to actually use.
What Is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body burns over 24 hours at complete rest — no movement whatsoever. It represents the energy required for basic survival functions:
- Maintaining body temperature (thermoregulation)
- Heartbeat and circulation
- Breathing and lung function
- Cell production, repair, and protein synthesis
- Kidney filtration and liver detoxification
- Brain function (the brain alone consumes roughly 20% of BMR)
For most adults, BMR accounts for approximately 60–75% of total daily calorie burn. For a sedentary person, BMR can represent as much as 85% of total expenditure. For a highly active athlete, it may be as low as 50%.
The Mifflin-St Jeor Formula
The most accurate widely-used formula for estimating BMR is the Mifflin-St Jeor equation, developed by M.D. Mifflin and colleagues in 1990. A 2005 meta-analysis in the Journal of the American Dietetic Association confirmed it as the most reliable predictive equation for resting metabolic rate in both obese and non-obese individuals.
Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
Example (35-year-old woman, 68 kg, 165 cm):
BMR = (10 × 68) + (6.25 × 165) − (5 × 35) − 161
BMR = 680 + 1,031.25 − 175 − 161
BMR = 1,375 calories/day
Use our BMR Calculator to get your number instantly without doing the math manually.
What Is TDEE?
Total Daily Energy Expenditure (TDEE) is the total calories your body burns in a real day — including all movement, digestion, and exercise. It is calculated by multiplying BMR by an activity factor (also called the Harris-Benedict activity multiplier):
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little to no exercise | 1.2 |
| Lightly Active | Light exercise 1–3 days/week | 1.375 |
| Moderately Active | Moderate exercise 3–5 days/week | 1.55 |
| Very Active | Hard exercise 6–7 days/week | 1.725 |
| Extra Active | Athlete or physical job + daily training | 1.9 |
Continuing the example above (BMR = 1,375, moderately active):
TDEE = 1,375 × 1.55 = 2,131 calories/day
That's the number of calories she needs to eat each day just to maintain her current weight. A 500-calorie deficit from TDEE = 1,631 cal/day for approximately 1 lb/week of fat loss.
Why TDEE Is the Number to Use
Using BMR as your calorie target is a mistake because:
- BMR assumes you're lying motionless in bed all day
- For a moderately active person, BMR can be 35–55% lower than TDEE
- Eating at BMR creates an unintentional, often severe calorie deficit that promotes muscle loss, fatigue, and metabolic adaptation
- Over time, eating at BMR is often unsustainable and leads to binge-restrict cycles
TDEE is your true maintenance — the calorie level where body weight stays stable. All calorie goal calculations for weight loss, gain, or maintenance should start from TDEE.
Common Mistakes to Avoid
- Confusing BMR with maintenance calories. Maintenance calories = TDEE, not BMR. Always apply an activity multiplier.
- Overestimating activity level. Most people are "sedentary" to "lightly active" by these definitions. Picking "very active" when you exercise 3 days/week inflates TDEE by 200–400 calories, making weight loss stall.
- Not recalculating as weight changes. BMR decreases as you lose weight — a 20-lb loss can reduce BMR by 100–150 calories. Recalculate every 10–15 lbs.
- Adding exercise calories to TDEE separately. If you use the activity multiplier method, your exercise is already baked into TDEE. Adding it again double-counts and inflates your target.
- Using outdated formulas. The older Harris-Benedict equation (1919) overestimates BMR for most modern adults by roughly 5%. The Mifflin-St Jeor equation is preferred.
Key Facts at a Glance
- BMR = calories burned at absolute rest; represents ~60–75% of TDEE for most adults
- TDEE = BMR × activity multiplier; the true daily calorie burn
- Mifflin-St Jeor is the most validated BMR formula as of a 2005 meta-analysis
- Sedentary multiplier: 1.2 | Lightly active: 1.375 | Moderately active: 1.55 | Very active: 1.725
- For a moderately active person, TDEE can be 55% higher than BMR
- Always use TDEE (not BMR) as the baseline for calorie goal-setting
- Recalculate BMR and TDEE every 10–15 lbs of weight change
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR is the calories burned at complete rest — just to keep your body alive. TDEE is BMR multiplied by an activity factor to account for daily movement. TDEE is always higher than BMR and is the number to use for setting calorie goals.
Which is more accurate for weight loss — BMR or TDEE?
TDEE, without question. BMR doesn't account for any of your daily movement. Eating at your BMR would create an unintentionally large deficit for most people, leading to muscle loss and metabolic adaptation.
What is the Mifflin-St Jeor formula for BMR?
Men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5. Women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161. A 2005 meta-analysis confirmed this as the most accurate general-population BMR formula.
What activity multiplier should I use for TDEE?
Sedentary = 1.2, Lightly active = 1.375, Moderately active = 1.55, Very active = 1.725, Extra active = 1.9. Most office workers who exercise 2–3 days per week fall in the 1.375–1.55 range.
What are common mistakes people make when using BMR vs TDEE?
The #1 mistake is treating BMR as a maintenance calorie level — it isn't. Others include overestimating activity level, not recalculating after significant weight changes, and double-counting exercise calories on top of a TDEE-based multiplier.