* Short-beaked echidna: 30-45 cm (12-18 inches) long, weighing 2-5 kg (4-11 lbs).
* Long-beaked echidna: 45-77 cm (18-30 inches) long, weighing 3-10 kg (7-22 lbs).
So, depending on the species, an echidna can be anywhere from the size of a small cat to a medium-sized dog!