The domestic cat has a smaller skull and shorter bones than the European wildcat. It averages about 46 cm (18 in) in head-to-body length and 23–25 cm (9.1–9.8 in) in height, with about 30 cm (12 in) long tails. Males are larger than females. Adult domestic cats typically weigh 4–5 kg (8.8–11.0 lb)
Cats have excellent night vision and can see at one sixth the light level required for human vision. This is partly the result of cat eyes having a tapetum lucidum, which reflects any light that passes through the retina back into the eye, thereby increasing the eye's sensitivity to dim light.Large pupils are an adaptation to dim light. The domestic cat has slit pupils, which allow it to focus bright light without chromatic aberration. At low light, a cat's pupils expand to cover most of the exposed surface of its eyes. The domestic cat has rather poor color vision and only two types of cone cells, optimized for sensitivity to blue and yellowish green; its ability to distinguish between red and green is limited. A response to middle wavelengths from a system other than the rod cells might be due to a third type of cone. This appears to be an adaptation to low light levels rather than representing true trichromatic vision. Cats have a nictitating membrane, allowing them to blink without hindering their vision.
The domestic cat's hearing is most acute in the range of 500 Hz to 32 kHz. It can detect an extremely broad range of frequencies ranging from 55 Hz to 79 kHz, whereas humans can only detect frequencies between 20 Hz and 20 kHz. It can hear a range of 10.5 octaves, compared to about 9 octaves for humans and dogs. Its hearing sensitivity is enhanced by its large movable outer ears, the pinnae, which amplify sounds and help detect the location of a noise. It can detect ultrasound, including ultrasonic calls from rodent prey. Research has shown that cats have socio-spatial cognitive abilities to create mental maps of familiar people's locations based on hearing their voices.
Outdoor cats are active both day and night, although they tend to be slightly more active at night. Domestic cats spend the majority of their time in the vicinity of their homes, but they can range a radius of many hundreds of meters. They establish territories that vary considerably in size, in one study ranging 7–28 ha (17–69 acres). The timing of cats' activity is quite flexible and varied; but being low-light predators, they are generally crepuscular, which means they tend to be more active near dawn and dusk. However, house cats' behavior is also influenced by human activity, and they may adapt to their owners' sleeping patterns to some extent. Cats conserve energy by sleeping more than most animals, especially as they grow older. The daily duration of sleep varies, usually between 12 and 16 hours, with 13 to 14 being the average. Some cats can sleep as much as 20 hours. The term "cat nap" for a short rest refers to the cat's tendency to fall asleep (lightly) for a brief period. Short periods of rapid eye movement sleep are often accompanied by muscle twitches, which suggests they are dreaming. Behavioral and personality traits depend on a complex interplay between genetic and environmental factors. Scientific evidence is mixed about the popular belief that those traits are linked to coat colors
