How the TDEE calculator works
Your total daily energy expenditure (TDEE) is the number of calories your body burns in a full day, including rest, movement, and digestion. It is the anchor for any eating plan: eat at your TDEE to hold weight, below it to lose, and above it to gain. This tool estimates TDEE in two steps: first your resting burn (BMR) from the Mifflin-St Jeor equation, then an activity multiplier.
Step 1: BMR from the Mifflin-St Jeor equation
Basal metabolic rate (BMR) is what you would burn lying still all day. The Mifflin-St Jeor equation is the widely used modern standard. It takes weight in kilograms, height in centimeters, and age in years:
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
If you enter imperial units, the calculator converts first: kg = pounds × 0.453592 and cm = total inches × 2.54. So 176 lb becomes about 80 kg and 5 ft 11 in (71 inches) becomes about 180 cm.
Step 2: Multiply by your activity level
BMR only covers rest. To get TDEE, multiply BMR by a factor that reflects how active you are:
| Activity level | Description | Multiplier |
|---|---|---|
| Sedentary | Little or 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 | Physical job or twice-daily training | 1.9 |
TDEE = BMR × activity multiplier. The gap between sedentary and extra active is large, so pick honestly. When in doubt, round down: it is easier to add food later than to unknowingly overshoot every day.
Turning TDEE into cutting, maintenance, and bulking targets
Once you know your TDEE, calorie goals are simple adjustments around it. About 3,500 kcal roughly equals one pound of body weight:
- Weight loss (cut): TDEE − 500 kcal, about 1 lb/week
- Mild weight loss: TDEE − 250 kcal, about 0.5 lb/week
- Maintenance: TDEE, hold steady
- Mild weight gain: TDEE + 250 kcal, about 0.5 lb/week
- Weight gain (bulk): TDEE + 500 kcal, about 1 lb/week
The calculator shows all five so you can see the full range at a glance.
A fully worked example
Take a 30-year-old man who is 180 cm tall, weighs 80 kg, and is moderately active:
- BMR = 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 800 + 1125 − 150 + 5 = 1780 kcal
- TDEE = 1780 × 1.55 = 2759 kcal/day (rounded)
From there, his cut target is about 2759 − 500 = 2259 kcal, and his bulk target is about 2759 + 500 = 3259 kcal. If he were sedentary instead, TDEE would drop to 1780 × 1.2 ≈ 2136 kcal, showing how much activity level alone changes the number.
Accuracy and a health disclaimer
Mifflin-St Jeor is accurate to within roughly 10% for most adults, but it cannot measure your exact body composition, so very lean or very muscular people may fall outside that range. The real test is your own trend: track your weight and intake for 2-4 weeks and nudge calories up or down 100-200 kcal if reality does not match the estimate.
These figures are educational estimates, not medical or dietary advice. Calorie needs vary with genetics, medication, and health conditions. Talk to a doctor or registered dietitian before major diet changes, especially if you are pregnant, managing a health condition, or planning a large deficit.