As the largest bird in the world, it’s understandable why you’d be curious about the growth of an ostrich. How big are the babies when they’re born? How fast do the chicks grow? At what age do these birds reach full maturity? All of these are valid questions. With mature ostriches towering over 9 feet tall, it’s no wonder why people are so intrigued by these flightless birds.

This article will tell you everything you need to know about the size of these birds as well as their growth patterns.


Facts About the Ostrich


There are two types of ostriches:  the Common ostrich (Struthio camelus) and the Somali ostrich (Struthio molybdophanes). Both of these ostriches are flightless birds, although they do still use their wings for mating, balance, dominance, and protecting their young. These birds can reach top speeds of up to 45 miles per hour thanks to their two long, strong legs and clawed toes. Their long necks provide an excellent vantage point in the wild that helps them see long distances and keep an eye out for nearby predators.

Ostriches have unique feathers compared to other birds. Instead of having sleek, tightly-packed wings, they have a shaggier look with looser feathers. The adult males have the signature black and white coloring, while immature birds and females are more brownish-gray in color.


Ostrich Size and Growth Chart

Ostrich standing in a dry field
Image Credit: polyfish, Pixabay

Ostriches are the largest and heaviest birds on the planet. The males tend to be larger than females and they range in size from 5½–9 feet tall and weigh anywhere from 200–350 pounds when they reach maturity. Believe it or not, their eggs are equally impressive. A single egg can weigh up to 3 pounds and be 6 inches in diameter!

Egg3 pounds6 inches
Newborn2 pounds10 inches
6 months150 pounds6 feet
3 years200 – 320 pounds5½ – 9 feet

When Does an Ostrich Stop Growing?


The life of an ostrich starts while the chicks are still in their eggs. A female ostrich can lay up to 25–50 eggs in a single season, with the season often lasting from March until September. Ostrich eggs are also some of the largest eggs in the world.

During the breeding season, a dominant male will perform a courtship dance by shaking his feathers. If the main hen of the herd is impressed, she will choose to mate with the male. Other hens mate with the dominant male or lesser males during this time as well. Males will then dig out a dirt nest and allow the dominant female to lay her eggs in the center of the nest. The rest of the females lay their eggs around hers, and a communal nest will have up to 60 eggs inside it. Males and females then take turns incubating the eggs.

ostrich with her eggs
Image Credit: LionMountain, Pixabay

Chicks and Adolescents

As long as the eggs are protected from predators like hyenas, vultures, and cheetahs, they will hatch after 6 weeks. Freshly hatched chicks are about the size of a full-grown chicken. They grow roughly 10–12 inches for every month during their first 6 months of life. Most ostriches that are 6 months old are nearly full-grown.

young ostrich bird
Image Credit: PublicDomainPictures, Pixabay


Ostriches reach full sexual maturity when they are between 3–4 years of age and they remain this size until the end of their lives. Wild ostriches live to be 30–40 years old, but those in captivity can live until 70 years old.


Factors Affecting the Size of Ostriches

flock of ostrich
Image Credit: Piqsels

There are several factors that can affect the size of an ostrich. One study shows that the size of the chicks at birth plays the most significant role in their adult size. Chicks were hatched and reared in groups of mixed sizes and weighed daily under identical conditions. The study found that chicks that weighed the heaviest at birth remained the heaviest. On the other hand, the smallest chicks grew more quickly than the larger chicks.

This study also showed that environmental factors also influenced the size of the birds. For example, the chicks that needed help with hatching had low growth rates and poor survival rates. Another study showed that protein levels and dietary energy affected their growth rates.

Ideal Diet for Maintaining a Healthy Weight

Wild ostriches are mostly found in the deserts and savannahs of Africa. These birds are omnivores and tend to eat roots, fruits, and flowers. However, some ostriches have a different diet depending on the food that is available to them. Ostriches will also eat insects, small tortoises, and lizards at times.

ostrich eating grass
Image Credit: Wirestock Creators, Shutterstock

How to Measure an Ostrich

There are four different measurements that you can take of an ostrich. Body height is the first, which measures the bird from the ground to the top of its head. Body depth measurements start at the topmost part of the back of their bottom fan behind their legs to the front of the body. Next, body length is taken from the base of the neck to the base of the tail. Lastly, body width is measured from the outside of the drum muscles and straight across the back.



The more you learn about ostriches, the more you understand how impressive these flightless birds are. They tower over humans, run as fast as cars, and have unique behaviors. If you’ve ever been up close to one, their size can be intimidating. Hopefully, this article explaining their growth rates from egg to adult helps you better understand how they reach such remarkable heights.

Featured Image Credit: Papa Bravo, Shutterstock