Things You'll Need
- Halter and lead rope, or cross ties
- Unsharpened wooden pencil
- Permanent marker
- Ruler
Instructions
Halter your horse and tie it by the lead rope in its stall, or place it in cross ties.
Slide the wooden pencil into the animal's mouth just as you would a bit and position the pencil on the "bars" of the gums. The bars in a horse's mouth are the open spaces on both upper and lower jaws between the canine teeth and the premolars where the bit normally sits.
Make a small dot with your permanent marker on either side of the pencil at the points where the horse's lips rest when its mouth is closed.
Remove the pencil and gauge the space between the dots with your ruler. Since most bits measure either in ¼-inch or ½-inch increments, round up to the nearest ¼ inch. This width determines the size of your bit.