What this calculator does
This TDEE calculator estimates how many calories your body burns per day. It first computes your basal metabolic rate (BMR), the energy you burn at complete rest, using the Mifflin-St Jeor equation, then multiplies it by an activity factor to get your total daily energy expenditure (TDEE). From there it suggests daily calorie targets: about 500 kcal below TDEE for steady fat loss, TDEE itself for maintenance, and about 300 kcal above for gradual muscle gain. For general information only: this is not medical advice.
How the math works
The Mifflin-St Jeor equation (1990), widely considered the most accurate common BMR formula:
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
- TDEE = BMR × activity multiplier (1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extra active).
Worked example
A 30-year-old man, 180 cm, 80 kg, moderately active. BMR = 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 1,780 kcal/day. TDEE = 1,780 × 1.55 = about 2,760 kcal/day. Suggested targets: roughly 2,260 kcal to lose, 2,760 to maintain, 3,060 to gain.
Choosing your activity level
Most people overestimate. A desk job with 3 gym sessions a week is "moderately active" at best; "very active" means daily hard training or a physical job. When between two levels, pick the lower one for a week, track your weight trend, and adjust. The scale over 2 to 3 weeks is the real calibration tool.
Limitations
These are population-average estimates. Muscle mass, hormones, medications, illness and metabolic adaptation all shift real expenditure, sometimes by several hundred calories. The calculator is a starting point, not a prescription. If you have a medical condition, are pregnant, or have a history of disordered eating, talk to a clinician or registered dietitian instead of dieting from a calculator. This content is general information, not medical advice.
Track composition, not just calories
TDEE tells you how much to eat, but not what your weight is made of. The body fat percentage calculator estimates your body fat from a few tape measurements, so you can tell whether a change on the scale is fat or muscle while you follow your calorie target.
Hydrate for the activity you chose
Your activity level drives water needs as well as calories. The daily water intake calculator turns your weight, activity, and climate into a hydration target in liters, glasses, and bottles.