How to measure your horse's mouth for a bit

An ill fitting bit can cause a multitude of problems for you and your horse including rubbing, pinching, improper application of pressure, sliding and connecting with the teeth. If you are having issues with your horse either being resistant to the contact, hesitant to take the contact, slow to react to the aids or on the other hand overreactive to the aids, then it is likely that your bit does not fit, or you are using the wrong bit for your horse. We are here to help you find the right bit for your horse!


Before measuring - points to consider

    • The length of the mouthpiece is measured from the inside of each cheekpiece to cheekpiece and is typically taken in inches or millimetres. 
    • 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.
    • Eggbutt and D-ring snaffles or any type of fixed ring or fulmer should rest comfortably against the outside of the horse's lips, while loose-rings should have an extra 1/8" to 1/4" to prevent pinching.
    • If your bit is even 1/2 inch too wide for your horse's mouth then it will slide and cause friction, rubbing and pinching. 

Measuring your horse's mouth

1. You can purchase a measuring device, or you can use a homemade device, such as a wooden spoon, piece of string, bailing twine or something similar. 

2. Either mark the end of the solid device or tie a knot in one side of the string. 

3. Place the device inside the horse's mouth as you would a bit. 

4. Ensure the device is sitting up against the corners of the lips and wait until your horse stops mouthing. Once the device is still, hold the other end of the device with your fingers to mark the place it sits against the lips. Wiggle the device side to side gently to ensure that there is no slide through. 

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 result is between sizes, we recommend sizing up.