How can I tell if my horse's bit fits??


This is a question with no easy answer - but there are lots of things to consider here.  Put it all together and you’ll have your answer. 


  • It fits the width of his mouth.  What I mean by this is that there is about 1/4 of an inch or more on either side of his lips when the bit is resting in his mouth.  Careful that there is not too much extra, as this causes the bit to slide side to side.  The reason for this is to keep the very fleshy lips away from any “pinchy” areas where the bit meets the bit rings.  




  • It fits the space in his mouth.  The space I’m referring to is the area between his upper hard palate and his bars. The bars are the semi-soft area between his upper and lower chompers.  Ideally, the bit should be no more than 1/2 of that space.  This is where your horse’s specific mouth anatomy (including tongue thickness and palate location) varies from your friend’s horse.  This is the exact reason why it’s not totally correct to say that “all thin bits are harsh”.  The reality is that some thin bits are actually thick in some horses!


  • It’s positioned correctly on the bars of the mouth.  Start in the middle, about halfway between the upper and lower teeth.  You may have heard the old saying about 1-2 wrinkles in the corner of the mouth being ideal.  This is another case in which anatomy sometimes bucks the rules.  Go for position on the bars and feel in his mouth when you are riding over wrinkles.  



The bars of the mouth are seen here, above and below the tongue where there are no teeth. 


  • It’s not interfering with his teeth, or his teeth aren’t interfering with his bit.  Regular inspections of his mouth by your Veterinarian and regular dental care can alleviate alignment issues as well as protect his gums.  This also allows your Veterinarian to create a “bit seat” if needed in his mouth.  A note about wolf teeth, too, which are the tiny tiny teeth that are usually removed while your horse is a very young fellow.  Sometimes they come back!  


  • It feels good to him and his palate.  Be mindful of two or three piece bits, as the inverted “V” shape created by these bits will press against the palate.  This is where test riding several bits and adjusting the bit in his mouth several times comes in handy. 




  • A word about home-made measuring devices.  While it’s a seemingly good idea to grab some rope or twine and use that to measure his mouth, I have an easier suggestion.  Grab a super clean bit from a friend and use that instead.  Rope, twine, or even a tape measure (yes, I spotted a website that suggested this) can abrade or scrape.  A real bit will mimic how a new one will actually fit.  Then you can bring it to the tack store and compare sizes and thicknesses.  


Any other ideas from you guys??