How daily calories are estimated
First the calculator estimates your basal metabolic rate (BMR), the energy your body uses at complete rest, with the Mifflin-St Jeor equation. Research has found it to be the most accurate of the common BMR formulas for most adults.
BMR is then multiplied by an activity factor to get your total daily energy expenditure (TDEE), the calories you burn on a typical day:
| Activity level | Multiplier |
|---|---|
| Sedentary | 1.2 |
| Light | 1.375 |
| Moderate | 1.55 |
| Very active | 1.725 |
| Extra active | 1.9 |
Example: a 30-year-old man who is 175 cm (5 ft 9 in) and 75 kg (165 lb) has a BMR of 1,699 calories. With moderate activity, his maintenance level is about 2,633 calories a day.
Using the numbers
A deficit of roughly 500 calories a day is often cited as about 1 lb (0.45 kg) of weight loss per week, but real-world results vary and slow down over time as your body adapts. Treat these figures as a starting point, track how your weight actually changes over a few weeks, and adjust gradually.
Frequently asked questions
Why is my result different from my fitness tracker?
Trackers estimate activity from heart rate and movement, which can over- or under-count. Both are estimates. Watching your actual weight trend over 2–4 weeks is the most reliable way to find your true maintenance level.
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest (breathing, circulation, organ function). TDEE adds everything else: daily movement, exercise and digesting food. TDEE is the number to use for planning meals.
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