When Do Horses Stop Growing?

Jessica McDaniel
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When Does a Horse Stop Growing in Height?

Horses are considered adults at 2 years old. After that they will not grow any taller. Adult horses do not have a set height. It is more of a range than a predetermined number.

When many people picture a horse they picture a large powerful horse. This is often referred to as the “cowboy horse”, and is the type of horse we see on the big screen.

However, not all horses have the same body structure. Some are designed for speed (Arabians and Thoroughbreds) while others are designed for strength (Draft horses). While there is no set height, there is a minimum height. Horses that are too small can't be used as riding horses.

In most horses the overall height of the body is greater than the length of the limbs. This is the reason a horse can carry its body weight on very small hooves.

A good way to see if your horse is at a healthy level is to make sure his withers is level with the ends of the ribs.

Many horses are kept in smaller facilities with less space. You can check if your horse is at the correct height by placing your hand under the horse's belly. If your hand touches the ground, your horse is too short. If you can’t easily reach the ground with your hand, your horse is too tall.

When Does a Horse Stop Growing in Weight

Height, and Body Size?

The growth of a horse is heavily dependent on its breed and its gender. The height reached by a horse can vary greatly from one breed to the next.

Many small breeds will never reach an adult body size. For example despite a horse being over 10 years old, these breeds will usually stay under 14 hands (on average). While horses are still considered miniature as adults, the body has stopped growing.

Some large breeds such as Draft Horses (percherons, Friesians, and Shires) can continue to grow in height until they reach 8 or even 10 years of age. Shetland ponies are also considered to be among the few breeds who don’t stop growing in height. Shetlands can grow in height until at least 16-20 years of age.

As for the weight gain of a horse, it is the same. Depending on its breed and gender and its purpose of use, a horse may or may not start gaining in size once it reaches adulthood. For example a quarter horse is expected to be fully mature by about 5 years, and may continue to grow in body size (weight gain) to almost 10 years of age (on average).

When Does a Horse Stop Growing: Bones

For the most part, horses stop growing around the age of four and a half to five years old. However, some horses will be done growing earlier, some a bit later. The growth plates, or physes, located in the long bones of the legs and the spine close when the horse is done growing and are unable to grow further. Of course, some breeds of horse, particularly ponies, have a shortened skeletal growth cycle.

Growth Plates

Horses grow from the day they are born and stop growing when their length reaches 133% of their height. Their growth plates remain active until they reach 60% of their expected height. During this time, their bones are soft and they are very vulnerable to injuries. It’s important to treat them gently and carefully to avoid breaking any bones or joints while they grow.

Once fully grown, contrary to popular belief, a horse’s growth plates actually stay inactive. It’s important to note that a fully grown horse can have active growth plates and can, in fact, still grow at that point.

Two of the most common growth plates that remain active are located on the humerus and femur bones. The remainder of the horse’s growth plates on most bones will actually remain inactive until the horse dies.

Bone Minerals

Bones are a complex system of individual hard parts (calcium, phosphorus, and fluoride), the blood cells, the organic bone matrix and the inorganic hydroxyapatite crystals. Bone cells are the source of those hard parts. As you can guess, the hard part crystals are what you want to look for in good bone mineral supplementation – the frazierite in OsteoMax and Bioplex, and potassium in OsteoMax and BioCal.

Zeolites are also in good bone supplement formulas. Zeolites are an even more porous, more advanced structure than silica, and are used to draw hard-part crystals from the bones into blood, which is how they make up for a deficiency. It bypasses the bone because it's just a contraption that can suck hard part crystals from bones directly into the blood.

All bones do not mature at the same rate, so the ideal is to find a bone supplement that builds all bones at the same time, and to have a serious deficiency in one, you need to be on them all at the same time.


Horses generally have a long life span, but they are not meant to live forever. Normal life expectancy is 20 – 25 years. Some horses live into the late 30’s and early 40’s. The tallest horse ever, measured at 19.2 hands (6 feet 2 inches), was a New Zealand Shire named Beau Brummel. I’m not sure if that is a confirmed record. Average horse height is about 16 hands. There is some evidence that French Stallion Marcheur ( Piccolo) died at age 62, which would be remarkable.

It’s hard to say “this is the average life span of a horse because it differs by breed, gender and geography. In northern climates horses can usually live longer due to the lower heat and the more comfortable nutritional environment. In hotter climates of the south and southwest horses usually have a shorter life span because of the heat.