How Big Is a Red Kangaroo? The Largest Marsupial's Size

Red kangaroo size at a glance

The red kangaroo shows one of the biggest size differences between the sexes of any mammal in Australia. A large male can weigh more than twice as much as an adult female.

Including the tail, a big male can measure over 2.5 m (8 ft) from nose to tail tip.

Why are males so much bigger than females?

Male red kangaroos compete hard for the chance to mate, and size wins fights. Heavier males with strong shoulders and forearms push, wrestle and kick more effectively, as described in why do kangaroos box? Over many generations, this competition has favored big males.

Males also keep growing for much of their lives, long after they become able to breed. Females grow more slowly once they start producing young, which takes a lot of energy. As a result, the gap between the sexes widens with age, and the biggest kangaroos in any mob are old males, which Australians call “big reds”.

Body condition changes with the weather. After good rains, kangaroos put on weight, while during long droughts they become thin and lighter.

How big is a newborn red kangaroo?

The contrast between adults and newborns is extraordinary. A red kangaroo joey is born after about 33 days of pregnancy, measuring roughly 2.5 cm (1 in) and weighing less than 1 g (0.04 oz). It grows in its mother’s pouch for around eight months and is weaned at about a year old. Read the full story in what is a baby kangaroo called?

Females can breed at about 15–20 months old, when they are still fairly small. Males take longer to reach a size where they can compete successfully, usually several years.

What is the biggest red kangaroo on record?

Large males often stand over 1.8 m (6 ft) tall. Exceptional males have been reported at around 2.1 m (6.9 ft) tall and about 90 kg (200 lb). Most such figures come from individual measurements rather than systematic studies, so they should be treated as rare upper limits rather than typical sizes.

Viral photos of extremely muscular kangaroos, such as a famous male at a kangaroo sanctuary in Alice Springs, have made “big reds” internet stars. These animals were impressive but still within the normal size range for large adult males.

How does the red kangaroo compare with other kangaroos?

Several other kangaroos are large, but none quite match a big red male in weight.

The eastern gray kangaroo can be about as tall as a red kangaroo, and some measurements of standing height even rival big reds, but it is usually lighter and slimmer.

Size also affects how kangaroos move. Larger kangaroos store more energy in their leg tendons with each bound, which makes hopping especially efficient for big reds. See how high can a kangaroo jump? for their leaps and speed.

Were there bigger kangaroos in the past?

Yes. During the Ice Age, Australia had giant kangaroos far bigger than any alive today. The largest known, the short-faced kangaroo Procoptodon goliah, may have stood around 2 m (6.6 ft) tall and weighed perhaps 200–240 kg (440–530 lb), several times the weight of a modern red kangaroo. It had a short, deep face and a single large toe on each hind foot. These giants died out tens of thousands of years ago.

How does a red kangaroo compare with people and other animals?

A big male red kangaroo is roughly the weight of an adult man and, standing tall, can look him in the eye or tower over him. A female is closer in weight to a child of about 8 to 12 years old. Among Australia’s native land mammals, no living species is larger.

Compared with familiar animals in Europe and North America, a male red kangaroo weighs about as much as a smaller white-tailed deer buck, while a female is about the size of a large dog.