Here is some advice from the top blanket manufacturers in the world: Weatherbeeta

How to determine your horses' blanket size:

Step 1: Measure your horse to find the right size.

a. Chest to Tail - from the center of the chest to the furthest rear point of the rump measuring along the side of the horse.

This measurement in inches will be the size for your blanket.

Step 2: Fasten and adjust the straps.

a. Chest Straps - fasten chest straps so fabric overlaps at the chest.

b. Leg Straps - pass the left leg strap between the hind legs and fasten to the left hand dee-ring. Cross the right leg strap through the left leg strap and fasten to the right hand dee-ring. Ensure the leg straps are adjusted so you can only fit a hand's width between each leg strap and each of your horse's thighs.

c. Surcingles - fasten belly surcingles and adjust straps to allow a hand's width between straps and belly.

Step 3: Check that your rug/blanket fits.

Your horse's rug/blanket fits when the chest closure is secured on approximately the middle adjustment and the top of the tail flap falls at the top of the tail.

That’s it!

Common problems/ Incorrect fitting rugs.

• A rug/ blanket that is too big is actually more likely to cause rubs than one that is too small, and this can be dangerous.
• If the rug/blanket extends beyond the top of the tail, the rug/blanket is too big. If the rug/blanket does not reach the top of the tail, the rug/blanket is too small.
• If leg straps and surcingles are not adjusted to allow a hand's width, your horse may get his legs caught in the straps if the straps are too long. If they are too short, the straps may rub.
• If the neck of the rug is too big, the rug/blanket will hang off the back of the horse, which will place pressure on the shoulders and increase the possibility of rubbing and slippage. The horse may also be in danger of stepping on the back of the rug when trying to stand after rolling.

Remember, if your horse is comfortable in his properly fitted rug/ blanket, he will be much happier to stay dressed.  A poorly fitted rug/blanket will be uncomfortable for your horse and he may try to get it off.  Taking the above correct fitting steps will ensure that your new blanket will not rub and will provide ultimate fit, protection and freedom of movement.