How to Measure the Mouthpiece of a Bit

A bit should fit your horse’s mouth so that the mouthpiece extends approximately 1/4 inch (0.6 cm) beyond the horse’s lips on either side, but not so tight that the horse might be pinched by any movable cheek pieces. You also don’t want a great length of bit hanging out of the horse’s mouth. The different parts of the mouthpieces on bits are made to sit on specific areas of the mouth. So for the bit to be effective, the bit needs to contact those areas properly. You also don’t want the bit pulling through the horse’s mouth when you pull on a rein.

There are a few ways to measure for the correct width.

Measure an old bit you know already fits. Use a tape measure to measure from the inside of each cheek piece or ring.

Use a piece of string about 12” (30cm) long. Tie a knot about 2 inches (5cm) in. Put it through your horse’s mouth, with the knot against the lips on one side. Mark the opposite side with a marker or little piece of tape.

Mark a piece of doweling the same as for the string.

Put a sewing tape measure through your horse’s mouth—the flexible cloth or plastic kind.

Use callipers. Adjust one arm of the calliper on either side of the horse’s mouth and then lay them down and measure the distance between the two arms of the calliper. Buying a pair of callipers for a one time measuring job is costly, so do this only if you have some available. (Buy it now)

Download, print and cut out a bit measurer. Neueschulebits.com Measurer Template

Write down the measurement and take a tape measure with you when you go out to buy a bit. At the store, ask if the bit is returnable if it doesn’t fit. When you get the bit home make sure that it sits comfortably in the horse’s mouth before you get rid of the receipt and packaging.