Your BMR is only the resting floor. This adds an activity multiplier to give your total daily energy expenditure — plus cutting and bulking targets built from it.
What each level actually means in practice.
| Level | Multiplier | Typical week |
|---|---|---|
| Sedentary | ×1.2 | Desk job, no deliberate exercise |
| Lightly active | ×1.375 | Light exercise 1–3 days |
| Moderately active | ×1.55 | Moderate exercise 3–5 days |
| Very active | ×1.725 | Hard exercise 6–7 days |
| Athlete | ×1.9 | Twice-daily training, or training plus physical work |
This page's own default — a 30-year-old man, 80 kg, 180 cm, moderately active — lands on a TDEE of 2,759 calories, and shows three targets built from it: a mild cut at 15% below (2,345), a standard cut at 20% below (2,207), and a lean bulk at 15% above (3,173). The mild option trades a slower rate of loss for an easier adherence bar — a smaller, more sustainable gap below maintenance rather than the sharper standard deficit.
Of the 2,759-calorie TDEE, 1,780 is BMR — resting metabolism — and the remaining 979 calories, 35.5% of the total, comes purely from the ×1.55 activity multiplier. Moving from moderately active to very active (×1.725) would add another 311.5 calories to the ceiling without changing anything about the body itself — the multiplier alone is doing that work, which is exactly why honestly picking an activity level matters as much as the BMR formula underneath it.
The Mifflin-St Jeor formula only ever sees age, sex, height, and weight — it has no way to know whether 80 kg is mostly muscle or mostly fat, and two people who share every input can have meaningfully different real resting metabolisms. The activity multiplier carries its own uncertainty in the same direction: it's a band, not a measurement, and most people round themselves up rather than down. Both errors tend to push the estimate in the same optimistic direction, which is exactly why tracking actual weight change over 2–3 weeks and adjusting is the step that turns this number from a guess into a working target.
BMR (basal metabolic rate) is what your body burns at complete rest just to stay alive — breathing, circulation, cell repair. TDEE (total daily energy expenditure) is BMR multiplied by an activity factor, so it also covers walking around, working, and training. BMR is the floor; TDEE is the realistic daily total, and it's the number you actually plan calorie intake against.
Sedentary (×1.2) is a desk job with little deliberate exercise. Lightly active (×1.375) is light exercise 1–3 days a week. Moderately active (×1.55) is moderate exercise 3–5 days a week. Very active (×1.725) is hard exercise 6–7 days a week. Athlete (×1.9) is twice-daily training or physical labour on top of training. Most people overestimate — if you're unsure between two levels, the lower one is usually closer.
The Mifflin-St Jeor equation, which has generally outperformed the older Harris-Benedict equation in validation studies against measured resting energy expenditure. For men it's (10 × kg) + (6.25 × cm) − (5 × age) + 5; for women the final term is −161 instead of +5. That BMR is then multiplied by your activity factor to reach TDEE.
It's a population-average estimate, typically within about 10% for most people but capable of being further off at the extremes of body composition. The equation doesn't know your muscle mass, and the activity multiplier is a broad band rather than a measurement. Treat the number as a starting point: track your weight over 2–3 weeks and adjust up or down based on what actually happens on the scale.
A deficit of roughly 15–25% below TDEE is a common cutting range, and a surplus of about 10–20% above TDEE is a common lean-bulking range — both shown above. Since roughly 7,700 calories is often cited as equating to one kilogram of body mass, a 500-calorie daily deficit works out to somewhere near 0.45 kg a week in theory, though real-world results vary with water weight, adherence, and metabolic adaptation.
Worked example: a 30-year-old man, 80 kg and 180 cm, has a BMR of (10×80) + (6.25×180) − (5×30) + 5 = 1,780 calories. At the moderately active multiplier of ×1.55 that's a TDEE of about 2,759 calories — so roughly 979 calories a day come from activity rather than resting metabolism. A standard 20% cut puts him near 2,207 a day, and a 15% lean bulk near 3,173.
Want the resting number on its own, or a macro split to go with this target? Use the Calorie / BMR Calculator and the Macro Calculator. To check how much a specific workout adds, try the Calories Burned Calculator, size your daily protein with the Protein Calculator, or check where your weight sits with the BMI Calculator. Training for a distance rather than a weight? The Pace Calculator converts between pace, time and distance. Once you have a calorie target, the Fat Intake Calculator turns it into daily grams of fat within the recommended 20–35% range. The equations behind this take weight in kilograms, so convert first with the pounds to kilograms converter if your scale reads in pounds.