How to Measure
Your Horse for Bit Size

Properly fitting a bit to your horse's mouth is essential, because the correct bit size allows you to communicate effectively. An improperly fitting bit can also be painful for the horse, as one that is too small can pinch and rub the sides of their mouth. A bit that's too big will also be ineffective, due to sliding around in your horse's mouth and making them more prone to get their tongue over the bit.

Furthermore, a horse bit that is too thick or thin can be a problem too. The mouth of a horse is filled with many sensitive nerves, and a bit places pressure in different ways on these nerves in the horse's mouth anatomy. That's why our staff has created this easy how-to guide, so you can always find the correct bit size and thickness for your equine!

• • Bit size (aka length) is measured straight across the mouthpiece from the inside of one cheekpiece to the inside of the other cheekpiece. This measurement is typically taken in inches.
  • The width, or thickness, of the bit is measured in millimeters and is taken at the widest part of the mouthpiece, typically next to the cheekpiece.
  • Bits that are too thick or too thin can impede upon your horse's comfort due to the increased tongue and bar pressure. Most horses have the mouth space to accommodate a bit that is 14mm thick.
  • It's always a good idea to check with your veterinarian or equine dentist to find out if your horse has any abnormal anatomy, such as a large tongue or low palate. These abnormalities may restrict the mouthpiece width or port height you choose.
  • Eggbutt snaffles and D-Ring snaffles should rest comfortably against the outside of the horse's lips, while loose ring snaffles should have an extra 1/8" to 1/4" to prevent pinching.
  • Bits that are 1/2" wider than the horse's mouth will have too much movement side-to-side, which will likely cause discomfort to your horse.

1. In order to measure your horse for a bit, you must first find a measuring device. Commercial devices are available to purchase; however, you can make your own by using a piece of heavy string or a smooth, straight stick.

2. If you use a homemade device, mark one end of it so you have a starting point.

3. Ask your horse to take the device in its mouth.

4. Hold the device on one side of the horse's mouth, where it was marked. Then use your other hand to mark the opposite side of the device where it meets the horse's lips.

5. Take the device out of the horse's mouth and measure the distance between the two marks. This measurement will correspond to your horse's bit size. If the measurement falls in between bit sizes, it is typically recommended to go with the larger size. A bit that is a slightly longer is less prone to cause rubs on your horse's lips.

It is imperative to choose the correct bit size and thickness for your horse's mouth, so they can feel comfortable and readily accept your communication aids. It can take time for your horse to become accustomed to a bit; however, your horse will ultimately tell you whether they are comfortable in their getup or not! Pay attention to your horse's response and continue to evaluate bit fit over time as your horse ages. If you are unsure whether the bit you currently have is the right one for you and your horse, we encourage you to read the rest of our horse bit guides for additional insight. Please feel free to contact our knowledgeable customer service team by calling 1(800)620-9145 or emailing info@ridingwarehouse.com if you have any questions or concerns regarding bits. Happy riding!