Like all falcons, peregrine falcons have long, tapered wings and a slim, short tail. In North America, peregrines are roughly the same size as crows. They weigh nearly 1 kilogram (2.2 pounds) on average. Like most birds of prey, female peregrine falcons are slightly larger than males.

There are 19 regional variants (subspecies) of peregrine falcon worldwide. These subspecies can be very different in size and color. Peregrine falcons have slate and blue-gray wings. They have black bars on their backs and pale underbellies. They have white faces with a black stripe on each cheek and large, dark eyes. Feather color doesn't change seasonally. Young birds tend to be darker and browner than the adults. Their underparts are streaked, rather than barred like adults.

Average mass: 907 g.

Range length: 36 to 58 cm.

Range wingspan: 91 to 112 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: female larger

Average mass: 840 g.