Heart girth
Body length

Measure Horse's Heart Girth (How do we do that?)

Please Note: Our Adult Horse Weight Calculator is meant for use solely as an estimation tool for the weight of a horse. Differences between individual horses are not considered. If the accuracy of the weight of the horse is absolutely necessary, please use a scale. TheGoodyPet is not responsible for undesirable circumstances that may arise from an inaccurate measurement of the horse's weight using this tool.
Useful Reads

How much medication should you give your horse?

Not sure how much feed or medication to give your horse? The first step to avoid underfeeding, overfeeding and overdosing is to find out the weight of the horse.

Other than wastage of money, overfeeding can also lead to undesired side effects. On the other hand, underfeeding can leave to stunted growth of the horse and that can be bad for the health and growth of the horse.

As for overdosing, undesirable side-effects can arise and that can be bad for the horse's health, both in the short term and in the long run.

Unfortunately, weighing an animal that is thousands of pounds heavy is not exactly an easy feat. That is why the adult horse weight calculation formula exists. This gives a pretty decent estimate of just how heavy the horse is allowing breeders and caretakers to make informed decisions.

So what exactly is needed for this calculation? And how useful is it really to monitoring a horse's growth and health trends? Well, let's find out.

Parameters required to calculate a horse's weight

Calculating a horse's weight includes using a formula with 2 main variables. These are the horse's heart girth and their body length.

More modern formulas also factor in the horse's age to give a more accurate estimation. Here is more on how to take the required measurements.

Horse Body Length

This is the length from the tip of the shoulder to a vertical plane against the horse's buttocks. It could be taken either in centimeters or inches which are then accounted for by different variations of the formula.

Horse Heart Girth

This is usually the more confusing of the two to measure. It is the circumference of the upper torso region roughly around where the horse's heart lays. In a lean, regular built horse, this is often the widest part of the torso. However, this may vary with breed, build, and general nutritional status.


Technically speaking, this is not a parameter used in the actual formula to calculate the horse's weight. However, the rule of thumb is that the horse should be at least more than 1 year old to get accurate results.

Horse Weight Formula

The two main parameters, the horse heart girth and horse body length>, need to be as accurate as possible in order to get a close estimate of the weight.

The formula itself varies in different publications. The most commonly recognized calculates the horse's weight as follows.

Weight in pounds = (Heart Girth in inches X Heart Girth in inches X Body Length in inches / 330

The constant in this case is the value 330 that was arrived at from research, trial, and error. This is also the value that varies from formula to formula with some using 300 as the constant.

We use 301 for yearlings (1 to 2 years old) and 285 for weanlings (less than a year old).

Fortunately, there are numerous online calculators designed to give you the best results. You just have to fill in the values from your measured parameters and with the click of a button you have an idea how much your horse weighs.

How accurate is it?

So is this method accurate? According to a 1998 report by J. M. Ellis and T. Hollands the calculation method is the most accurate of estimation methods for a horse's weight including estimation by sight.

However, there is room for error with variations in body type, breed build, and age.