When Do Horses Stop Growing? Insights And Responses

When is a Horse Fully Grown

Like many other animals, horses go through various stages of growth and development throughout their lives. One question that horse owners and enthusiasts often ask is, when do horses stop growing?

Understanding this includes determining when a horse is fully grown, how to monitor it, and whether it is no longer developing. This article will investigate these and other topics surrounding the growth of horses.

Two dressage horses

The Various Horse Growth Stages Explained

Horses go through several stages of development, including fetal, neonatal, weanling, yearling, and adult stages. Specific physical and behavioral changes mark each stage, and horse owners must know these changes to provide the appropriate care and training.

Here are the horse growth stages from birth to adulthood.

The Foal 

This stage begins when a horse is born and lasts approximately six months. During this period, foals typically double their weight and height, and their permanent teeth replace their milk teeth. The foals also begin eating substantial food, which is crucial for their growth and development.

The Weanling 

Weanling is a term for horses between six months and one year. This stage is weaning a foal from its mother’s milk and relies solely on solid sustenance for nutrition. This period is crucial for horses as they mature and thrive physically.

The Yearling

A yearling is any male or female horse between one and two years old as it continues to grow and develop rapidly during this time. Horses also develop their dispositions and behaviors, which impact their future performance and training. 

A male horse under four is a colt, while a female horse under four is a filly.


Adolescence is when a horse reaches puberty, and growth slows substantially. Two-year-old horse growth is slower, but it continues to mature and grow while beginning training for riding and other activities. 

Adult Horse

Adult horses undergo various growth stages before reaching full physical and mental maturity. So when is a horse fully grown? Typically, a horse will reach its full height and weight by age four or five.

However, even though full-grown horses have reached their optimum physical growth, their mental and emotional development may continue beyond this age. Many trainers recommend waiting until a horse is six years old before beginning intense training or competition. 

Waiting allows the horse to mature and fully develop physically and mentally. Ultimately, the exact age at which a horse stops growing can vary depending on various factors, including genetics, nutrition, and overall health and wellness.

How to Monitor Horse Development

Knowing how to monitor your horse’s growth is essential now that you understand the various phases of equine development. Here are the ways to monitor the growth and development of your horse.

Routine Veterinary Examinations

Veterinary examinations are essential for monitoring your horse’s health and growth. Your veterinarian can physically examine your horse and track their growth and development and other medical issues.

Regular Measurements

Regularly measuring your horse’s height and weight allows you to monitor their growth and development. 

Observing Conduct and Behavior

Your horse’s behavior can also shed light on its maturation and growth. Is the horse lively and playful, or does it appear lethargic and uninterested? Are they consuming food and liquids normally? These are all essential details to monitor.

How Can You Tell How Big a Horse Will Grow?

One of the most frequently asked inquiries about horses is how large they will grow. There is no foolproof method to forecast a horse’s final height and weight, but several factors can provide an estimate.


It’s important to note that there is a wide range of horse breeds, each with unique characteristics and size ranges. For example, draft horses such as the Clydesdale and Percheron are typically much larger and heavier than Arabian horses, known for their smaller, more refined build. 

Genetics is one of the most significant factors determining a horse’s size. If both parents of a horse are large and heavy-boned, it is more likely that their offspring will also be larger and more robust. 

Conversely, if both parents are smaller and more refined, their offspring will likely follow suit. Breeders can use selective breeding to influence the size and characteristics of their horses. Still, it is essential to remember that genetics is only one factor among many that can affect a horse’s size, build, and overall development.


Proper nutrition is also important for the horse’s overall health and well-being. A well-balanced diet can help ensure that a horse’s bones, muscles, and organs develop properly and can also help prevent certain health issues such as obesity, dental problems, and digestive disorders. 

The specific nutritional needs of a horse can vary depending on various factors, including its age, breed, activity level, and overall health status. Horse owners must collaborate with an experienced veterinarian or equine nutritionist for a feeding plan that meets their needs. 

This plan may include providing access to high-quality hay or pasture, supplementing with grain or other concentrates as needed, and providing access to fresh, clean water at all times. Owners can help support their growth, development, and overall health and well-being by ensuring their horses receive proper nutrition.


Stallions, which are male horses, are typically larger than mares, also known as female horses. This difference is because male horses have higher testosterone levels, contributing to increased muscle mass and bone density. Stallions may also have a larger frame and more pronounced physical characteristics, such as a thicker neck, a broader torso, and larger hooves. 

However, it is essential to note that size can vary significantly between males and females and that genetics, nutrition, and exercise can contribute to a horse’s overall size and stature. Also important to note, stallions are typically larger than mares; there are many instances in which mares can be physically more imposing than stallions, especially in certain breeds and lineages. 

Although factors can indicate how large a horse will grow, it is essential to remember that each horse is unique and may not fit the average size range for its breed or gender.

At What Age Do Horses Mature Mentally?

Similar to humans, horses undergo distinct phases of mental development as they age. A horse attains mental maturity from the age of four. They have developed the cognitive and emotional skills necessary for safe training and riding at this stage.

However, knowing that each horse is unique and may attain mental maturity at a slightly different age is essential. Some horses may reach mental maturity sooner, while others may take longer.

Beautiful brown horse standing

How Do I Know If My Horse Has Stopped Growing?

At what age do horses stop growing? Horse owners need to understand the different factors that can contribute to a horse’s growth and development. One important factor is nutrition, as a well-balanced diet can provide the necessary nutrients for a horse’s bones, muscles, and organs to develop properly.

Regular exercise and proper healthcare are also crucial for supporting a horse’s growth and development. Genetics also play a role, as certain breeds may grow larger or develop specific physical characteristics. Environmental factors such as climate, housing, and socialization can also impact a horse’s growth and development. 

By considering these various factors, horse owners can help ensure their horses reach their full potential in size, strength, and overall health. Ultimately, while there is no specific age at which a horse is fully grown, careful attention to these factors can help support a horse’s healthy growth and development.

If you are unsure whether your horse is still growing, there are a few telltale symptoms to watch out for, which consist of the following:

Height Stabilization

Once a horse has attained its maximum height, it will typically stop growing and stabilize. The typical height of a fully grown horse usually ranges from 14 to 17 hands or 56 to 68 inches (1.4 to 1.7 meters) at the shoulder.

Growth plates are the areas of cartilage at the ends of bones that allow for growth and will close as the bones mature. Once these growth plates fuse, bones cannot grow longer. The growth typically occurs between the ages of four and six in horses. 

Weight Stabilization

Once a horse reaches its maximum height and stops to grow taller, its weight should stabilize. Depending on the breed, a full-grown horse can weigh anywhere from 900 to 2,200 pounds (408 to 998 kilograms) 

If you are uncertain whether your horse has stopped growing, consult with your veterinarian, who can conduct a physical exam and take measurements to determine whether or not your horse is still growing or has attained its full size.

Skeletal Maturity

Horses, like all mammals, go through a process of skeletal development as they grow and mature. The skeletal system serves as the body’s framework, sustaining the horse’s weight and allowing it to move and engage in various activities.

Understanding the process of skeletal maturity is vital for horse owners and handlers, as it can affect the horse’s health, performance, and longevity.

The process of skeletal development in horses begins at birth and continues throughout the horse’s life. At birth, a foal’s skeleton is mostly cartilage, which is softer and more pliable than bone. As the foal grows and develops, this cartilage gradually transforms into bone, known as ossification. When the horse reaches maturity, its skeleton is fully formed and composed of hard, strong bones.

The timeline for skeletal maturity varies depending on the horse’s breed and size. Generally, smaller horses tend to mature faster than larger ones. For example, a pony may reach skeletal maturity in three or four years, while a larger horse may take five or six years to develop fully. It is important to note that skeletal maturity differs from physical or mental maturity, which may take longer to develop.

One key factor that can affect the process of skeletal maturity in horses is nutrition. Adequate nutrition is essential for the growth and development of strong, healthy bones. Horses that are malnourished or fed an imbalanced diet may experience delays or deficiencies in skeletal development, leading to various health problems, including bone fractures and joint issues.

In addition to nutrition, other factors that can impact skeletal development in horses include exercise, genetics, and environmental conditions. Overworking or overexerting a young horse can put undue stress on its developing bones, while genetic factors may influence the horse’s skeletal structure and growth rate. Environmental conditions like uneven footing or poorly designed stables can also affect the horse’s skeletal health and development.

Does Breed Influence the Maturity of a Horse?

Horse breeds vary in their growth rates and development, with some reaching their full size and maturity earlier than others. So when do horses reach maturity? The breed of a horse will influence maturity, as discussed below.

Quarter horses, known for being fast and useful, are generally muscular and compact, with a powerful build that allows them to excel in various activities, from racing to ranch work. So when do quarter horses stop growing? Usually reach their full height and weight by the time they are four or five years.

Thoroughbreds, bred for their speed and agility, reach their full size and maturity by four or five years old. These horses are tall and lean, with long legs and sleek bodies, making them ideal for horse racing and other competitive sports.

Arabian horses, one of the oldest and most recognizable horse breeds, tend to grow more slowly than other horses. Most horses reach their full height between the ages of four and five, but Arabian horses reach their full height around six years. 

Arabian horses’ skeletal structures have one fewer vertebra and one less pair of ribs than other horses, which may contribute to their slower growth rate. These horses are known for their endurance and grace, with a distinctive head shape and high-set tail.

Draft horses, bred for their strength and size, tend to reach their full size and maturity later than other breeds. Depending on the breed, draft horses can develop for five to seven years. These horses are massive and muscular, with a gentle disposition that makes them popular for work and recreation.

Understanding the growth rates and development patterns of different horse breeds can help owners and handlers provide appropriate animal care and training. By tailoring their approach to each horse’s unique needs and characteristics, they can help them reach their full potential and thrive.

When is a Horse Ready to Ride?

Physical and mental development, training, and breed are just a few variables that affect a horse’s readiness to mount. Some varieties, such as Arabians, may mature earlier and be suitable for riding at approximately two years old. 

Other varieties, such as draft horses, may take longer to mature physically and mentally and may not be suitable for riding until they are approximately six years old.

Before exercising a horse, one must consider its training, experience, and age. A horse trained well and exposed to different things will handle the riding challenges better than one without training. Consult a knowledgeable trainer and veterinarian to decide when to start riding a horse. 

Should I Speed Up My Horse’s Growth Rate?

Accelerating your horse’s growth rate may be alluring, but it is essential to remember that adequate nutrition and care are essential for a horse’s growth and development. Attempting to accelerate a horse’s growth rate through excessive nutrition or supplements can harm their health and lead to joint problems and growth plate damage.

Instead, focus on providing your horse with a well-balanced diet that satisfies their nutritional requirements, ample exercise, and space to move around.

How to Measure a Horse for Growth

Regular measurements are a smart place to begin if you want to track your horse’s growth over time. Here’s how to measure the development of your horse.


Use a measuring rod to determine the height of your horse. Place the pole at the base of the horse’s front forefoot and extend it until it reaches the withers’ highest point. This method will provide an accurate height measurement for your horse.


To determine your horse’s weight, you have a few options. One way is to use a scale, which provides a precise measurement. Alternatively, you can use a flexible weight tape that wraps around your horse’s girth to estimate its weight based on measurements. Remember that while a scale may be more accurate, weight tape can be more convenient.

Physical Condition

Evaluating your horse’s body condition score is essential. Assess the horse’s overall physical condition, including muscle tone, fatty deposits, and health.

By regularly checking your horse’s height, weight, and body condition score, you can track their growth and development and ensure they receive the appropriate care and nutrition to support their growth.

Horse portrait in nature

Key Takeaways

Growth and development in horses is a multifaceted process involving physical and mental maturation. At what age a horse will stop growing will depend on many factors. 

By understanding the various stages of horse growth and development and how to measure and monitor a horse’s growth, you can ensure that it receives the appropriate care and nutrition to support its growth and development.

It is important to remember that horses have several developmental stages, namely foal, weanling, yearling, adolescence, and adulthood. Nutrition, exercise, and genetics can all influence the growth and development of a horse.

Measuring a horse’s height, weight, and physical condition score allows you to monitor their growth and ensure they receive appropriate care and nutrition.