Enter your sex, age, height, weight and activity level. The calculator estimates how many calories your body burns at rest, then multiplies by your activity level.
Mifflin–St Jeor resting energy: men = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5; women = the same − 161. Daily needs = resting energy × activity factor (about 1.2 for little exercise up to about 1.9 for very active).
A 30-year-old man, 80 kg and 180 cm: 800 + 1,125 − 150 + 5 = 1,780 calories at rest. With light exercise (× 1.375) that is about 2,448 a day to keep his weight.