Smallest Domestic Cat Breed:
The Singapura is regarded as the smallest cat breed. Females weigh around 5-6lbs (2kg), while males weigh a little more at 6-8lbs (2-3kg).
However, there are now a group of cats that are called Dwarf cats. These are normal cats, but due to a dwarfism gene, they have very short legs. The most well-known short-legged cat breed is the Munchkin, but now there are several Drawf breeds due to crossing the Munchkin with other breeds of cat.
It should be noted that "teacup" and "miniature" cats are not recognized cat breeds, and are often results from mating undersized, and often unhealthy cats.
Smallest Cat Species:
The smallest cat species is commonly believe to be the Rusty Spotted Cat. It measures just 14 to 17 inches (35 to 48 cm) in the body and head and a further 6 to 10 inches (15 to 25 cm) for the tail. They weigh about 3.3 pounds (1.5 kg) on average, but can weigh as little a 2.2 pounds (1 kg), some times even less.
The Rusty Spotted Cat is commonly accepted to be smaller than the Black Footed Cat, who is a very close second. The Black Footed Cat can measure anywhere from 14 to 21 inches (36 to 52 cm) in the body and a further 5 to 8 inches (13 to 20 cm) for the tail. The smallest these cats can weight is 2.9 pounds (1.3 kg), but the average weight is nearer 3.5 pounds (1.6 kg).