Metabolism guide
BMR vs RMR vs TDEE
Updated October 11, 2026 · MyPlate
BMR is resting energy, RMR is a resting measurement, and TDEE is the whole day. Our calculators estimate the resting piece with Mifflin-St Jeor. TDEE is that number times an activity factor. Set a calorie target from TDEE. Eating your BMR is not the same as eating at maintenance.
The three abbreviations get stacked in search results as if they were three competing formulas. They are three scopes. Basal metabolic rate is the energy used for breathing, circulation, and cell work when a person is fully at rest, usually defined with strict lab conditions. Resting metabolic rate is measured at rest too, but the conditions are looser, so a lab RMR is not identical to a lab BMR. Total daily energy expenditure adds movement and the rest of living. For a website calculator, the honest move is to show the equation, show the activity step, and not pretend a form is a metabolic cart.
Side by side
| Term | What it covers | Use it to |
|---|---|---|
| BMR | Complete rest | See the floor of daily burn. BMR calculator |
| RMR | Rest, less strict conditions | Same practical job on this site. RMR calculator |
| TDEE | Rest times activity | Set maintenance. TDEE calculator |
The equation
Mifflin-St Jeor (American Journal of Clinical Nutrition, 1990):
- Men: (10 × kg) + (6.25 × cm) − (5 × age) + 5
- Women: (10 × kg) + (6.25 × cm) − (5 × age) − 161
Activity factors used on the TDEE page: 1.2, 1.375, 1.55, 1.725, and 1.9. Maintenance calories are the maintenance calorie calculator output, which is this same TDEE idea under a "maintain" label.
Worked example
A 35-year-old man, 90 kg, 178 cm.
10 × 90 = 900. 6.25 × 178 = 1,112.5. 5 × 35 = 175. Men: 900 + 1,112.5 − 175 + 5 = 1,842.5, which rounds to about 1,843 kcal. That is the BMR estimate. It is also the RMR estimate on this site, because both calculators use this equation.
Light activity, factor 1.375: 1,843 × 1.375 is about 2,534 kcal. That is TDEE, the maintenance estimate. A deficit comes off 2,534, not off 1,843. Taking 550 kcal off TDEE for about 0.5 kg a week leaves about 1,980 kcal. Taking 550 off BMR would leave about 1,293 kcal, which is a much harsher plan and is the usual mix-up. The calorie deficit calculator uses the TDEE path.
Common mistakes
- Calling BMR your "calories per day" and eating that amount while also walking to work.
- Expecting the RMR calculator to print a different equation. On this site it does not.
- Using a very high activity factor for a desk job with three workouts. The factor is for the typical day, not the best day.
- Never recalculating after weight changes. A smaller body has a smaller BMR from the same equation.
Sources
Open the BMR, RMR, and TDEE calculators, then how many calories should I eat.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the energy a body uses at complete rest. TDEE is BMR multiplied by an activity factor, so it includes the rest of the day. You compare food intake with TDEE.
What is RMR?
Resting metabolic rate is a resting measurement taken under less strict conditions than a true basal test. In practice many calculators, including ours, estimate it with the same Mifflin-St Jeor equation used for BMR.
Which number should I eat?
To maintain weight, eat around TDEE. To lose weight, eat under TDEE. Eating at BMR ignores walking, work, and training, so it is a deeper cut than it looks.
What equation do these calculators use?
Mifflin-St Jeor, published in 1990. Men: 10 times kg plus 6.25 times cm minus 5 times age plus 5. Women: the same, minus 161 instead of plus 5.
What are the activity factors?
A common set is 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, and 1.9 for very heavy training. Pick the factor that matches a typical week.
Do BMR and RMR calculators give different numbers here?
They share the Mifflin-St Jeor estimate. The pages differ in what they tell you to do next: the RMR page stays on the resting number, and the TDEE page multiplies by activity.