Measuring your horse’s mouth is a crucial aspect of fitting the correct bit. For this there is a very simple piece of equipment; the bit measure!
Measuring the width is an easy procedure provided one knows what to look for. Using a bit measure or straight rod, put it in the horse’s mouth and lift it to the correct place in the mouth, just before any wrinkles begin to form mark the bar on both sides just outside the lip crease. Measuring between these marks gives you the measured mouth size.
You can measure a correctly fitting bit. To do this lay the bit flat and measure the distance between the insides of the cheekpieces. Be sure to include the type of mouthpiece and cheekpiece of the bit that you measured so that we can calculate the correct size of the new bit.