Tack n' Talk

Online Equestrian Resource

Is Your Bit The Right Size?

By Larissa Cox

Recently, I attended a conference where a prominent clinician was performing and selling his products.  One of the items being sold was his recommended array of bits.  Looking at all the bits hanging on the wall,  I noticed that all the bits were of one size…5 inches.

We, as people don’t have the same foot sizes, we all differ in length, width and foot shape. Now wouldn’t this same logic apply to the horse’s mouth that each horse would be different?  When I asked the sales associate why each and every bit was 5 inches, the reply was the 5 inch bit is the most common bit and it generally fits 99% of horses.  Interesting…

Now, I own three horses.  Different breeds.  Different sizes.  So, according to the sales associate, a 5 inch bit should fit 2.9% of my 3 horses.  Basically a 5 inch bit should fit all three. Okay, now let us measure each horse.

Bruq, my 15hh Arabian gelding, measures at a 5 ¼ inch bit.

Phantom, my 16.1 Oldenburg, measures a 5 1/2  inch bit, and

Rio, my 17.1hh Hanoverian, sports a whopping 6 ¾ inch bit!

Not one of my horses would be fitted with a 5 inch bit!

While some horses have custom fit saddles, proper leg protection and a great nutrition program, many horses are still expected to perform in a bit that is either too small or too large for their mouths.  Like many horse enthusiasts, you may not recognize that your horse has a problem with his bit.  How does he try to tell you?  The only way he can, through his behavior and bit evasions. Many evasions may not be that obvious but can be annoying habits that prevent your horse from relaxing and giving you his best.  What often appears as a training issue, can be as simple as an ill fitting bit! A common misconception is that a horse with a painful mouth will be especially sensitive to bit cues. In fact horses tend to push into pain.

Behavior problems resulting from an ill fitting bit.

Recognizing bit resistance is important when dealing with some behavior issues.  Most common resistance issues can be:

  1. Bit chomping or open mouth
  2. Teeth grinding
  3. Leaning against your hand
  4. Staying behind the bit, putting his nose to his chest, or
  5. Keeping his head high, nose up in the air
  6. Head shaking or head tossing
  7. Hanging his tongue out
  8. Not moving forward
  9. Lack of lateral suppleness
  10. Tightness at the poll
  11. Backing up
  12. Bolting
  13. Bucking
  14. Sour horse, difficulty tacking up.

So, before you hang that bridle on your horse’s head, make sure that the bit is the proper size.  Most experts agree that a bit that is not sized correctly not only causes excess pain and discomfort, but cannot work effectively.  To determine if your current bit is the appropriate size, put the bit in the horse’s mouth and hold one ring of the bit against the corner of the lips and cheek without indenting them. Gently pull the other bit ring until the two arms of the mouthpiece are aligned. If the horse’s lips are pulled inwards, then the bit is too short. On the other hand, if more than ½” of mouthpiece protrudes then the bit is too long.

Dr. Hilary Clayton, veterinarian at MSU, conducted a radiographic study of bits in July 2005 and observed that riders and trainers have long believed that horses “lean on the bit,” or travel on their forehand, because they’re naturally (or have become) insensitive to the pressure or effect of the bit. But her studies have shown that the opposite is really true, that horses lean on the bit to relieve the pressure on the soft tissues of their palate.  In addition, Dr. Clayton believes that bit size is a more crucial measurement than most people think.  She advises measuring the width from lip to lip on your horse, and adding ¼” to get the proper measurement for your bit.

Choosing the correct bit size is not a science but does require knowledge.  Trying to do it yourself without that knowledge could result in a lot of frustration and wasted money.  Do not assume that every trainer is experienced and knowledgeable about bitting.  If you are unsure, check with a custom bit manufacturer and please measure your horse’s mouth!  Remember that not all horse’s are a size 5 bit!

Happy riding – Larissa  🙂


  Is Your Bridle Too Tight? « Tack n' Talk wrote @

[…] without the proper bit size, you may encounter negative horse behavior.  Please see my article, “Is your bit the right size” to get more information on proper bit […]

  Reanne Rudy wrote @

My 3 year old TB mare constantly throws her head and is now starting to refuse to trot. She won’t buck or bolt or anything, and it’s not like she’s purposely being mean or misbehaving. I have been riding since i was 6 and have never had this happen with ANY previous horses. I asked a really experienced friend of mine to measure her mouth and she said she was a five. My horse, Myla, has never done this except for the past two times I’ve ridden her, she is not sore in the spine as i have checked. She does have one cut on her front left leg, but its scabbed over and doesn’t seem to be bothering her. Could this be her bit or possibly her bridle?

  tackandtalk wrote @

If you haven’t read my article https://tackandtalk.wordpress.com/2010/04/18/bits-and-bitting-part-1-snaffle-bits/, please do and then take your horse’s measurement. It’s relatively easy to do. If you don’t have any tools, take a piece of twine and put it in your horse’s mouth where you would put the bit…measure from side to side on the twine with your fingers. Take it out and measure it against a tape measure and add 1/2 ince (1/4 inch for either side). That is your bit size. If your horse is acting up, I would suggest making sure the bit is the correct fit. If it isn’t, then buy the appropriate size and the appropriate bit for your use. Good luck!

  A BIT OF ADVICE « Tack n' Talk wrote @

[…] Too many people rely solely on the bit, saying if the bit doesn’t work, then they’ll try one with a longer shank or one with a thinner mouthpiece or twisted wire!  If that doesn’t work, then other artificial aids will control the horse.  It is very unfortunate that many people rely on a 5 inch bit and do not measure the horse’s mouth for the proper bit size. […]

  Teri J. Dluznieski M.Ed. wrote @

hell, I have 3 TB’s all between 16hh and 16.3hh… and even THEY don’t take the same size bit. Now I feel compelled to go back and recheck my bits and sizing.

Is there some way you can show some pics of this size-check process? That would be really helpful.

thanks a bunch!


  Bits and Bitting Part 1: Snaffle Bits | Tack n' Talk wrote @

[…] roof of the mouth is a very soft and sensitive mouth area.  Too much pressure here will cause the horse to react, often negatively, either by opening his mouth, tipping his head or tucking his chin into his […]

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