How To Estimate Your Horse’s Body Weight – [Average Weight by Breed]

Knowing your horse’s body weight is important to determine their nutritional requirements, administer certain medications and monitor their health status. However, not all horse owners have an easy way to measure their horse’s body weight.

Mature adult horses can weigh anywhere between 300 – 1000 kg (650 – 2200 lb) and require special weighbridges or scales to assess weight. On-farm scales are rare, and unless your horse travels to a local animal hospital, you may never get an accurate body weight measurement.

Fortunately, several methods are available to estimate your horse’s weight. This includes using a weight tape or calculating their approximate weight from girth and body length measurements.

It’s also important to know your horse’s body condition score and ideal body weight based on their breed and size. Reference ranges for various breeds exist so you can track whether your horse is overweight or underweight.

Why Do I Need to Know my Horse’s Body Weight?

Accurately determining your horse’s body weight is important for many reasons, including establishing nutrition requirements and formulating a balanced diet.

It’s also important to track weight changes over time so you can determine how well your horse’s feeding plan is meeting their energy requirements and make appropriate adjustments.

Nutrient Requirements

In the National Research Council’s Nutrient Requirements of Horses, the daily requirements for various macronutrients and micronutrients are based on the horse’s body weight and physiological status. ^[1]

If you work with an equine nutritionist to formulate a feeding program, one of the first questions they will want to know is how much your horse weighs.

For horses at maintenance, daily requirements are solely based on body weight (BW) in kilograms. Example calculations in the NRC include: ^[1]

• Dry matter intake: 0.02 kg of intake per kg of body weight (0.02 x BW)
• Digestible energy: 0.033 mcal per kg of body weight (0.033 x BW)
• Crude protein: 1.26 grams per kg of body weight (1.26 x BW)
• Calcium: 0.04 grams per kg of body weight (0.04 x BW)
• Phosphorus: 0.028 grams per kg of body weight (0.028 x BW)
• Magnesium: 0.015 grams per kg of body weight (0.015 x BW)
• Sodium: 0.02 grams per kg of body weight (0.02 x BW)

Calculations for exercising horses also take into account estimated sweat losses based on exercise level. Growing horses, lactating and gestating mares and stallions will also have different requirements than maintenance horses.

Many commercial feed tags list their recommended feeding levels on the basis of body weight. Under- or over-estimating your horse’s weight can lead to feeding inappropriate amounts.

Evaluating Weight Changes

Along with measuring body weight, you can assess whether your horse needs to gain or lose weight by evaluating their body condition. On the Henneke 9-point scale, an ideal body condition is 5 out of 9.

Surveys in Australia and the United Kingdom show that horse owners often underestimate their horse’s body condition. ^[2][3] This can lead to over-feeding to support weight gain in horses that are already at optimal weight or overweight.

Combining accurate assessment of body condition and your horse’s body weight can help properly assess whether your horse needs to gain or lose weight.

Weight Gain

Underweight horses may be affected by dental issues or gut health concerns such as gastric ulcers or internal parasites that make it harder to gain weight. These horses are often referred to as hard keepers.

Before adjusting their diet to support weight gain, consult with your veterinarian to identify underlying causes that may be contributing to poor body condition.

To support weight gain from a body condition score of 4 towards 5, the NRC recommends feeding 1.8 – 6.7 mcal of digestible energy per day above maintenance requirements. The amount depends on how quickly you would like to achieve weight gain. ^[1]

Horses that are beginning with a body condition of 1 – 3 need to be carefully managed to avoid metabolic concerns related to weight gain, such as refeeding syndrome.

Weight Loss

To promote weight loss, your horse’s digestible energy intake should be restricted to 64 – 94% of maintenance requirements. This is roughly equivalent to restricting their hay to 1.25 – 1.5% of their body weight. ^[4]

Horses that are resistant to weight loss may require further restriction. However, this needs to be balanced against the risk of gut health and behavioural issues if forage intake is too low.

Adding straw or choosing mature hay are options that allow higher forage intake while supporting weight loss. Soaking hay is another option to reduce calories in forage by reducing sugar content. This can allow higher hay intake in a weight loss program. ^[4]

It is recommended to target a rate of weight loss between 0.5% – 1% of body weight per week. Aiming for faster weight loss can put your horse at risk of hypertriglyceridemia – a potentially life-threatening metabolic state. ^[4]

Medication Dosages

The amount of medication that your horse needs is dependent on their weight. For example, the recommended dose of omeprazole used to treat gastric ulcers is 4 mg / kg of bodyweight.

An incorrect weight estimate could lead to your horse getting a dosage that is lower or higher than what they need. In a survey of 17 horse owners, 23.5% were giving an incorrect dose of prescribed medications. This can impact efficacy, side effects and cost. ^[5]

Providing a lower dosage could cause the medication to be less effective, while a high dosage could increase the risk of adverse reactions.

Calculating Carrying Capacity

The general recommendation is that horses should not carry more than 20% of their body weight, which includes both tack and rider. Heavier loads can contribute to a higher degree of muscle soreness and tightness. ^[6]

A small study in Warmbloods found issues with gait symmetry and lameness when carrying more than 15% of their body weight. ^[7]

Knowing your horse’s body weight can help you determine the maximum amount they should carry, especially if they are unconditioned or entering work.

How to Determine Your Horse’s Bodyweight

Here are several ways to determine your horse’s body weight, ranked from the most accurate to the least accurate.

1) Using a Scale

This is the most precise and reliable way to determine your horse’s body weight. Since large animal weigh scales are expensive, they are not accessible to the typical horse owner or small farms.

However, some feed representatives or veterinary practices may have portable scales that can be used.

2) Girth and Body Length Measurement

If a scale is not available, you can estimate your horse’s body weight using length and girth measurements. This is considered the most accurate way to estimate weight. ^[8][9]

To obtain your horse’s body length and girth length:

1. Ensure your horse is standing square
2. Measure their girth: place a measuring tape or string around your horse’s girth, directly behind their elbow
3. Measure body length: place a measuring tape or string at the point of the shoulder and measure to the point of the buttock. You will want another person to hold one end of the tape or string for an accurate measurement.
4. For both measurements, ensure the tape is snug but not tight. Check for twists in the tape and measure after the horse has exhaled.

Input these values into the calculator below to estimate your horse’s body weight.

The following nomogram can also be used to estimate equine body weight by drawing a straight line from the girth (cm) to the length (cm). The weight measurement can be read where the line crosses the centre axis. ^[13]

3) Weight Tape

A weight tape allows horse owners to take a simple measurement of the horse’s girth and immediately shows the corresponding weight estimate. Weight tapes are cheap and easily purchased at any tack or feed store and immediately provide the horse’s estimated weight.

To obtain a good estimate of weight, the weight tape needs to be used properly and consistently.

1. Wrap the tape around the horse’s girth. It should be over the withers and fitting snugly behind the elbow
2. The tape should be snug, but not tight
3. Take a reading when your horse has exhaled.
4. Take several measurements and take the average weight of the measurements

Different brands of weight tapes can use different proprietary formulas to estimate a horse’s weight. There can be a wide variation in estimated weight when using different weight tapes, so ensure you use the same weight tape each time.

4) Estimation by height and body condition score

Several studies have analyzed how different body measurements are related to a horse’s body weight. Researchers have found that body length and heart girth are more correlated with body weight than the horse’s height. ^[8][10][11]

This means that if you were to use a single measurement to estimate your horse’s weight, it should be the girth measurement rather than the height.

However, if you are solely measuring height, use the following nomogram to estimate weight from height and body condition score.

Draw a straight line from your horse’s body condition score to their height. At the point where the line crosses the centre axis is an estimation of the horse’s weight. ^[13]

Note that this uses a body condition score scale of 0 to 5 where:

• Score 0 (Very poor) – skin tight over ribs and angular pelvis
• Score 1 (Poor) – ribs easily visible, rump sunken but with supple skin
• Score 2 (Moderate) – ribs just visible, rump flat on either side of backbone
• Score 3 (Good) – ribs just covered, pelvis covered by fat and rounded
• Score 4 (Fat) – slight cresty neck, pelvis covered with soft fat, ‘gutter’ to the root of tail
• Score 5 (Very fat) – marked cresty neck, ribs buried, pelvis covered with soft fat and skin distended

5) Estimation of weight by breed

Based on measurements from 637 horses, Catalano et al. (2019) established breed-specific calculations of body weight using: ^[10]

• Girth: Circumference at the third thoracic vertebra (withers)
• Height: At the third thoracic vertebra
• Length: From the point of the shoulder to a line perpendicular to the point of the buttock.
• Neck: Circumference at the midway point between the poll and the withers

The following calculations, using all measurements in inches, estimated actual body weight within 4% of scale measurements. ^[10]

Arabians and ponies

Stock horses

Draft horses

Warmbloods

Miniature Horses (Mature)

For those three years or older and having a wither height less than 34 inches.

Miniature Horses (Growing)

For those three years or younger and having a wither height less than 34 inches.

Saddlehorse

Thoroughbred

Estimating Foal Body Weight (0 – 6 Months)

Measuring the weight of a young foal helps determine if they are developing at a healthy rate. However, the techniques used to estimate body weight were designed for adult horses and are not accurate for growing horses

A scale is the best way to determine the rapidly changing body weight of a young foal. In the absence of a scale, this formula can be used to help estimate a foal’s weight: ^[12]

To estimate the foal’s girth measurement, snugly place a weight tape behind the foal’s elbow and 1 inch (2.54 cm) behind the highest point of the withers. Record the measurements after the foal has been exhaled. Input the girth measurement into the formula in metres.

This study was performed using only Thoroughbred foals and has not been validated by subsequent research.  Different formulas use several other body measurements, resulting in slightly more accurate weight estimates.

Since it is very difficult to get foals to stand still for accurate measurements, researchers suggest using the simpler formula to help track growth rates. ^[12]

Predicted Weight

Knowing your horse’s predicted mature weight based on its breed can help you determine whether your foal is meeting growth targets.

For a growing horse that will reach a mature weight of 500 kg / 1,100 lb, estimated weights are: ^[1]

• 4 months: 169 kg / 373 lb
• 6 months: 216 kg / 476 lb
• 12 months: 321 kg / 708 lb
• 18 months: 388 kg / 855 lb
• 24 months: 429 kg / 946 lb
• 36 months: 472 kg / 1041 lb

In general, the percent of mature body weight that a growing horse should weigh can be estimated by the following equation where M is the horse’s age in months: ^[1]

Factors Affecting Growth & Weight

Note that a foal’s weight can be impacted by many factors, including:

• Mare’s milk production and colostrum quality
• Health history
• Season and pasture availability
• Creep-feeding
• Breed
• Exercise level

These should be taken into consideration when interpreting a growing horse’s weight. Any concerns should be raised with your veterinarian and nutritionist.

Some growth abnormalities can occur due to nutritional imbalances and may be improved by appropriately adjusting the diet. Examples of conditions affecting growing foals include developmental orthopedic disease, big head disease, and rickets.

Average Horse Weight Chart by Breed

Below are the average weights of different breeds of horses. The actual weight will be dependent on the horse’s age, conformation and body condition score.

Pony Breeds

Light Breeds

WarmBloods

Draft Breeds

 
These weights should be considered general guidelines that you can use to assess your horse’s body weight. If you have concerns, you can submit your horse’s information, including weight, body condition, and diet, to our nutritionists for guidance on managing their weight.