It is important to ensure you choose the right sized bit for your horse. A bit that’s too-small can pinch and cause rubs on the tongue or cheeks, and a bits that’s too-big can slide around in the mouth and be less effective.
Bits are measured from inside corner to inside corner, across the length of the horse’s mouth. The easiest way to find the correct size bit for your horse is to measure a bit you already have that you know fits well. To measure the size of the bit, simply measure the length of the mouthpiece only, excluding the rings or shanks. This measurement (in mm or inches) corresponds to the size of bit you require.
Standard horse size bitss include 5”, 5 ¼”, and 5 ½” (130mm, 135mm, 140mm.) Pony bits can run as small as 3”, and draft horses be as large as 7”.
For snaffle bits, you should see 1-2 wrinkles at the corner of the mouth and tension on the cheek pieces without solid pressure. You won’t see any wrinkles for curb bits, but the bit should be resting against the corners of the horse’s mouth and should not be low enough to touch or bang on the teeth.
