Wondering what is the best way to measure your horse for a bit size? There are a number of ways on how to measure a horse for their bit size.
If you have a few bits spare you can try them in the horse's mouth and this will rule out too small or too big. A general rule for sizes is
Mini pony= 3.5 inch
Small pony/Shetland = 4 inch
Pony= 4.5 inch
Galloway 14-15hh= 5"
Hack= 5.5 inch
Warmblood/shire or draft= 6 inch
There are of course exceptions to this rule such as breeding for example- a riding pony bred Galloway tend to have fine facial features and noses so may take a 4.5 inch bit. A thoroughbred hack may be over 15hh but may have a fine muzzle so takes a 5 inch bit.
A horse bit should be a comfortable size in your horses mouth otherwise it may become uncomfortable for your horse and causes issues such as behaviour, lip or tongue chaffing.
To check if your bit is the right size in your horses' mouth you can follow some simple tips
If your bit is too big, you will see considerable space from the edge of your horses mouth to the end of the bit. A bit that is too big will pull through your horses mouth from side to side and not allow even contact through the paces or turning. Pictured below-
A horse bit that is too small will pinch the side of your horses mouth. You will not see any space and the corner of the lips will look jammed up. Every time you ask your horse for direction, they will experience the uncomfortable feeling of the rings almost in their mouth. Pictured below-
A good fitting, comfortable horse bit will fit comfortably in the space of your horses mouth with only the tiniest edge of the bit peeking out. Pictured below-
To check the size of your horse bit, lay your bit down flat to measure. Be sure to turn it so you are measuring the inside of the cure of the bit as this is the side that goes in your horses mouth. Pictured below-
Grab a tape measure and measure the distance of the bit from inside grove across. Be sure that you are measuring the distance from the inside as this is the exact distance the bit will measure. As you can see from the photo. this bit measures at 5 inches. Pictured below-
A bit fitting specialist may have a bit fitting measurer tool which slides in your horses mouth like a bit and the side can be moved in or out to determine the exact size. Most horse bits will come in half inch increments but some speciality brands of bits will make 1/4 inch bits.
A horses thickness of tongue, lips and pallet will all determine the most comfortable and best fitting bit possible. Trial and error are often the best ways to determine if your horse likes or is suited to that type of bit.