What is resting energy expenditure?
REE, often used interchangeably with Resting Metabolic Rate (RMR), is the energy your body uses at complete rest over 24 hours. It typically accounts for 60-75% of the total calories you burn each day, which is why it's the starting point for working out how much to eat.
REE vs BMR vs TDEE
These terms are closely related and often confused. BMR (Basal Metabolic Rate) is measured under strict laboratory conditions after fasting and rest; REE/RMR is measured under slightly less strict conditions and comes out a few percent higher - in everyday use the two are treated as the same. TDEE (Total Daily Energy Expenditure) is your REE multiplied by an activity factor to include movement and exercise.
How this calculator works
The calculator uses the Mifflin-St Jeor equation, widely regarded as the most accurate of the common predictive formulas. It then multiplies your REE by an activity factor to estimate your TDEE, your maintenance calories.
Worked example: a 70 kg, 175 cm, 30-year-old man has an REE of about 1,649 kcal. If he's moderately active (×1.55), his TDEE is roughly 2,556 kcal per day.
Example REE and TDEE estimates
These examples show how quickly calorie needs change with body size, sex and activity level. They are not targets to copy, but they make the output easier to sanity-check.
| Profile | REE | Light activity | Moderate activity |
|---|---|---|---|
| 70 kg, 175 cm, 30-year-old man | 1,649 kcal | 2,267 kcal | 2,556 kcal |
| 60 kg, 165 cm, 35-year-old woman | 1,295 kcal | 1,781 kcal | 2,008 kcal |
| 90 kg, 180 cm, 40-year-old man | 1,830 kcal | 2,516 kcal | 2,837 kcal |
Activity multipliers
To turn REE into total daily calories, multiply by the factor that matches your lifestyle.
| Activity level | Multiplier |
|---|---|
| Sedentary (little exercise) | × 1.2 |
| Lightly active (1–2 days/week) | × 1.375 |
| Moderately active (3–4 days/week) | × 1.55 |
| Very active (5–6 days/week) | × 1.725 |
| Athlete (intense daily training) | × 1.9 |
How to use REE for your goals
Once you know your TDEE, set calories relative to it: eat at maintenance to hold weight, around 10-20% below for fat loss, or 5-15% above for muscle gain. Because REE depends partly on lean mass, building muscle gradually raises your resting calorie burn, making weight management easier over time.
Hold any new target steady long enough to judge it. Two to four weeks of body weight, waist measurements, energy, hunger and workout performance will tell you more than one calculated number.
Why predicted REE can be wrong
REE formulas estimate an average person with your age, sex, height and weight. Real people vary. Lean body mass, body fat percentage, dieting history, thyroid status, medications, illness, sleep loss and recent weight change can all move actual REE above or below the prediction.
That is why the calculator should be treated as a starting estimate. If your weight trend does not match your expected calorie balance after several consistent weeks, adjust the target based on real tracking data rather than assuming the formula must be exact.
How to increase your resting metabolic rate
Because muscle is metabolically active, the most effective way to raise your REE is to build and preserve lean muscle through regular resistance training. Every kilogram of muscle you add nudges your resting calorie burn upward and makes weight management easier.
Other levers help too: eating enough protein supports muscle and has a high thermic effect, staying physically active throughout the day (not just during workouts) keeps expenditure up, and avoiding very aggressive crash diets prevents the metabolic drop that comes with rapid weight and muscle loss. Adequate sleep and managing stress round out the picture.