TDEE calculator
The gap between the lowest and highest multiplier is over half again as much energy. For the default figures, about 1,300 calories a day. Choosing the band is a bigger decision than any of the measurements, so it is worth seeing the alternatives rather than one number in isolation.
A population estimate, not a measurement. Real expenditure varies by around 10% between people of identical size, and the activity multipliers are broad bands rather than precise factors.
Total daily energy expenditure is what you burn in twenty-four hours: your basal metabolic rate multiplied by an activity factor between 1.2 for a desk job and 1.9 for physical work or twice-daily training. Basal rate alone: what the body uses at complete rest; is typically sixty to seventy per cent of the total.
How to use this calculator
Expenditure has three parts. Basal rate is the largest and is what the equation estimates. Digestion accounts for roughly a tenth. The rest is movement, and that includes fidgeting, walking and standing, not only exercise, which is why two people with identical training can differ by several hundred calories a day.
Questions
BMR is what you would burn lying still all day. TDEE is BMR plus digestion and everything you actually do. TDEE is the figure to eat against.
Whichever describes a normal week including the days you do nothing. Most people should choose one band lower than instinct suggests.
Mifflin–St Jeor predicts resting rate within about ten per cent for most people. The activity multiplier is much rougher, so treat the total as a starting point and adjust from what the scale does over a fortnight.
Some, but less than commonly claimed. A kilogram of muscle burns roughly 13 calories a day at rest, against about 4 for a kilogram of fat.
This one tells you what you burn. The calorie calculator takes that and turns it into a target for a weight goal.