How to Measure Your Horse for a Rug: Masta Size Guide

Getting the right rug size is one of the most important things you can do for your horse's comfort and welfare. A rug that fits well protects your horse from the elements, allows freedom of movement, and lasts considerably longer. A rug that doesn't fit is a different matter entirely - it can cause pressure sores, restrict the shoulder, slip and become a safety hazard, or simply fail to do its job.

This guide walks you through how to take an accurate measurement, how to use the Masta sizing chart, and how to check the fit once the rug is on.

Step 1. Stand your horse on level ground. Make sure he is standing square and is not wearing a rug.

Step 2. Place the end of the tape at the centre of his chest, at the point where the neck meets the shoulder (point A).

Step 3. Run the tape around the widest part of his shoulder, along his side, and straight to the centre of his tail (point B). Keep the tape level and reasonably taut.

Step 4. Note the measurement in centimetres or inches.

Step 5. Deduct 4 inches (10cm) from this figure. This is your horse's rug size.

Find your nearest size in the chart below. Masta rugs are sized in 3-inch increments, so most horses will fall between two sizes. In that case, round up rather than down.

This chart is a guide. Height alone doesn't determine rug size - body shape, width, and build all affect fit.

Two horses of identical height can need quite different rug sizes. A broad, cobby horse with wide shoulders may need to go up a size from what the chart suggests, while a fine, narrow thoroughbred-type may need to go down. If your horse is particularly wide through the barrel, factor that in when deciding between sizes.

Similarly, horses with large or high withers benefit from a rug with room through the shoulder - a rug cut too short through the neck can sit back and press directly on the withers, which is one of the most common causes of rug rub.

Once the rug is on, work through these checks before removing any tags.

At the front: Fasten the chest straps and slide your hand inside the rug at the front. You should be able to move it freely over the shoulder without resistance. If it won't pass, the rug is too small through the chest. If there's excessive movement, it may be too large.

At the withers: The rug should sit two to four inches in front of the withers, not pressing down on them. Pressure here will cause rubbing over time.

At the shoulder: Watch your horse walk a few steps. The rug should move with him, not drag back or restrict his front legs. A rug that's too small will pull tight across the shoulder; one that's too large will slip back.

At the belly: Fasten the surcingles so you can fit a hand's width between the strap and your horse's belly. Too tight pulls the rug down onto the withers; too loose and your horse can get a leg caught when he rolls.

At the tail: With your horse's head at normal grazing height, the back of the rug should reach the top of the tail without hanging over it. Rugs drop forward slightly when the horse grazes, so check this with his head down.

If your horse measures right between two sizes, a few things are worth thinking through.

Time of year. In winter, a slightly larger rug may be more comfortable over additional layers. In summer, a closer fit on a lighter sheet is usually preferable.

Age and condition. Older horses and those losing condition may benefit from a roomier fit for comfort. Young horses in work may fill out and need reassessing each season.

Workload and clipping. A horse that has been clipped will lose some of the natural coverage that helps a rug sit correctly, so fit may need to be reassessed. A horse in hard work may carry more muscle through the shoulder than the same horse at rest.

As a general rule, when in doubt, size up - a rug that's a touch too long is safer than one that's too short.

Check regularly for rub marks, particularly at the shoulders, withers, and chest. Rub marks at the shoulder typically indicate a rug that's too small, while marks at the chest or withers usually point to a rug that's too large and slipping back. A loose rug may also move excessively in wind, making it uncomfortable and reducing its protective performance.

If you notice any rubbing, remove the rug and reassess the size before putting it back on. Don't assume the horse will settle in - a rug that's causing rubs on day one will continue to cause them.

Rug sizing is not fully standardised across the industry. A 6ft Masta rug may fit slightly differently to a 6ft rug from another manufacturer. If you're switching brands or buying Masta for the first time, always measure fresh rather than relying on a size you've used elsewhere.

Now you've got your measurement, browse the full Masta range - from the award-winning Fieldmasta dome neck turnout to the therapeutic Protechmasta far-infrared stable rug. Every rug is designed to fit correctly from first use, with adjustable fastenings to fine-tune the fit for your horse's individual shape.

Shop Masta Turnout Rugs

Shop Masta Stable Rugs

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Do I measure my horse with or without a rug on?

Always without. A rug adds bulk and will give you a false reading, meaning the new rug is likely to be too large. Stand your horse square on level ground before you start.

What if I don't have a long enough tape measure?

Use a length of baler twine instead. Run it from chest to tail as you would a tape measure, mark the point with your finger or a knot, then measure the string against a shorter tape or ruler afterwards.

My horse is between two rug sizes, which should I choose?

Size up as a general rule. A rug that's slightly too long is safer than one that's too short. The exception is a very fine or narrow horse, where a larger size may slip. In that case, try both if possible before committing.

Why does height in hands not always match the rug size chart?

Because height alone doesn't tell the full story. A 15.2hh cob and a 15.2hh thoroughbred can need quite different sizes due to differences in shoulder width, body length, and overall build. Always go by the chest-to-tail measurement rather than height.

What does the deduction of 4 inches (10cm) account for?

The 4-inch deduction adjusts for the curve of the horse's body. Measuring around the outside of a rounded shape gives a larger figure than the actual length of rug needed to sit flat. The deduction brings the measurement in line with the flat-measured rug sizes used by manufacturers.

How do I know if my horse's rug fits correctly?

Once the rug is on, you should be able to slide your hand freely inside the front, around the chest and shoulder. The rug should sit two to four inches in front of the withers without pressing down on them. With the horse's head lowered to grazing position, the back of the rug should reach, but not hang over, the tail. 

Can I use my horse's existing rug size as a guide?

With caution. If the current rug fits well, you can lay it flat and measure from front edge to back as a cross-reference. Bear in mind that older rugs may have stretched, and that sizing varies between manufacturers, so always cross-check with a fresh measurement.

How often should I re-measure my horse?

At minimum, once a season. Horses change body condition through the year - gaining muscle in work, losing weight in hard winters, or filling out as youngsters develop. A rug that fitted well last autumn may not be right by spring.

What causes rug rub marks?

Rub marks at the shoulder usually mean the rug is too small and restricting movement. Marks at the withers or chest tend to indicate a rug that's too large and slipping back. If you notice any rubbing, remove the rug and reassess the size before using it again.

Do Masta rug sizes match other brands?

Not always. Rug sizing is not standardised across the industry, so a 6ft Masta may fit differently to a 6ft rug from another brand. Always measure fresh when switching to Masta for the first time rather than relying on a size used elsewhere.