How to weigh a horse and monitor changes

Weighing a horse accurately isn’t usually that easy; most yards aren’t equipped with an equine equivalent to bathroom scales, which would make things much easier. Nevertheless, knowing how to weigh a horse – or how to work out if they sit within their ideal weight range – is an important equine management skill.

There are three standard methods for determining a horse’s weight: applying a weight estimation formula, using a weigh tape, or a weighbridge. Below, we’ll explore how these methods work and their pros and cons with expert input.

Why is weighing horses important?

Katie Reeve, an equine nutritionist at Dengie, highlights several reasons to have an accurate picture of your horse’s weight – including how much hay to feed your horse.

“Having an accurate weight for your horse helps to ensure they are receiving enough forage in their diet,” she says. “This is particularly helpful if they are on a restricted ration to help promote weight loss.

“Once the horse’s weight is known, we can then calculate 1.5% of their bodyweight to ensure there is enough fibre in their ration. It can also help ensure you feed the correct quantity of products like feed balancers to provide the horse with the vitamins and minerals they need.”

Katie adds that knowing your horse’s weight is helpful for practical reasons, too.

“Knowing your horse’s weight ensures correct dosage for deworming and medication or making sure you aren’t exceeding the payload in your horsebox.”

How much should my horse weigh?

You can find weight estimations on the back of feed bags, but a good indicator that your horse is in the right weight range is having an optimal body condition score. In the UK, body condition score is measured on a scale of 0–5. An optimally healthy horse scores between two and three.

“Knowing your horse’s body condition score is arguably more important than the number on the scales,” says Katie. “It tells you if your horse is carrying a healthy amount of bodyweight or if they are overweight or underweight.”

Katie gives the example of two horses, both 500kg, one with an optimal body condition score of 3/5 and other 5/5.

“Although the two horses weigh exactly the same, the first horse has a much healthier body condition score and the second is very overweight,” she says.

“In this instance, it is the body condition score that tells us how healthy the horse actually is and if there are any changes that need to be implemented in their ration.”

A close up of a hand holding a yellow weigh tape against a horse's brown fur

Weigh tape readings are not accurate, but can give an indicator as to how a horse’s weight fluctuates. Credit: Alamy/Susan Norwood

How to estimate a horse’s weight

There’s a formula you can use that’s designed to estimate a horse’s weight – you just need a calculator, a long measuring tape with centimetres, and possibly a helper.

The two measurements you need to know are:

Your horse’s heart girth (the distance around the whole torso behind the elbows), and;
Your horse’s body length from the point of shoulder to the point of buttock.

Then, the formula you use to calculate the weight in kilograms is:

(Heart girth (cm) x heart girth (cm)) x body length (cm) ÷ 11877

While useful as a guide, there are flaws the formula, such as the fact that doesn’t take body condition into account. It is most useful when used alongside a weighbridge so the figures can be compared.

How to use a weigh tape

“Weigh tapes [like this one available on Amazon] are very useful for tracking weight, especially when used regularly,” says Vanessa Allen, nutritionist at Spillers. “We suggest weekly for those who need their weight monitoring for gains or losses.

“They may not be accurate, but are a useful guide and confirm if your horse’s weight is going in the right direction.”

Step by step

Emma Short, senior nutritionist at Baileys, says…

Make sure your horse is standing square – bearing in mind some horses can be nervous on their first weigh tape encounter.
On their near side, keep the end of the tape in your right hand and pass the rest of the tape over the horse’s back, behind the withers.
The tape needs to sit where the girth normally goes, just behind the front legs. It should be pulled snug to depress the flesh very slightly.
Read the weight by overlapping the tape and taking the measurement at the arrow.

Pros and cons of weigh tapes

While weightaping is quick, convenient and home-based, it can’t be relied upon as an accurate measure.

“In overweight horses, weigh tapes typically slightly underestimate bodyweight,” says Emma. “This is because the tape does not account for any fatty deposits over the neck or around the tailhead.

“Body length is also not accounted for on the tape, so horses with longer backs may come up slightly lighter on the tape.”

Katie adds that a combination of measures can work best. “In an ideal situation, you should weigh tape your horse at the same time as using the weighbridge,” she explains.

“You can then use the weigh tape more frequently to easily monitor the horse’s weight in between weighbridge sessions.”

Women wearing a hard helmet weighs a bay horse on a weigh bridge

Horses must stand perfectly still on a calibrated weigh bridge to record an accurate weight. Credit: Bex Pattenden

How to weigh a horse with a weighbridge

You can weigh your horse at a public weighbridge, or some feed companies and vets have portable devices to bring along to yard visits.

“Using a weighbridge will always be the most accurate reading for your horse,” says Katie. “It should be used alongside regular body condition scoring and weigh tape readings to monitor fluctuations.”

Step by step

Topspec’s veterinary nutritionist Anna Welch says…

If using a portable scale, position the weighbridge on a firm, flat, level surface with a straight, unobstructed approach and exit.
Calibrate or sense-check the weighbridge with a known weight, such as a bag of feed or a full water container.
Approach confidently with your horse, like you would a trailer ramp. Look ahead, allowing him time to investigate, sniff and pause if needed.
For an accurate reading, your horse should be straight, centred, and standing completely still on the weighbridge. If he becomes anxious, it may help to step off and re-approach.

A man wearing a read tshirt and safety helmet calibrates a weighbridge.

Weighbridges must be calibrated before use. Credit: Bex Pattenden

Using a weighbridge for the first time

Vanessa says she has weighed thousands of horses, and of those only a handful refused to go on.

“Even if they have a little snort or are suspicious to start with, if the owner is confident and walks straight across it their horse will usually just follow,” she says.

“Some owners will walk around it and their horses follow them, seeing the weighbridge as something to avoid.”

Vanessa says it takes only a couple of seconds to register the weight, so a well-handled horse should be fine after a couple of practice runs.

“I’d recommend owners follow instructions from the nutrition advisor who brings the weighbridge,” she continues. “We’re really experienced and genuinely know all the tips if a horse is shy to start with.”

Pros and cons of using a weighbridge

Anna says as well as providing greater accuracy than a weigh tape, it means you can be sure you’re supporting your horse with an accurate feeding and worming programme, and precise doses of medication too.

“Limitations include limited access to a weighbridge, which makes regular monitoring a challenge,” she adds. “Errors can occur due to uneven footing and failing to zero the weighbridge, and accurate readings depend on your horse standing completely still.”

Anna says the biggest error owners can make is ignoring body condition because the weight in kilos seems acceptable.

“When weighing your horse, make sure you replicate the conditions,” she says. “For example, if you ride to a weighbridge and weigh your horse in his saddle, make sure to do the same next time.”