How To Determine Western Cinch Size
Before you can determine the correct cinch size for your horse you'll need to understand some cinch basics.
Cinches have both a length and width measurement. The length is measured from the outside of one ring to the outside of the opposite ring. Sizes come in two-inch increments between 26 and 36 inches. The most common sizes are 30”, 32” and 34”.
Width is measured either in inches or, on cord cinches, by strand count. Strand counts can vary between 14 and 31 strands. A cinch can be either “straight” with a uniform width, or a Roper style, with the width wider in the middle.
The correct cinch size for a particular horse will place the center strip of the cinch in the middle of the underside of the horse and the cinch rings approximately 8 inches below the rigging plates. Your cinch rings should be high enough so that they fall above your horse's elbow, so as not to interfere with your horse's movement or cause irritation from rubbing on the rings.
To measure your horse for the correct size, place your saddle on the horse while he's standing on level ground. Tie a piece of string or baling twine to one rigging ring, loop it under the horse's girth, and bring it up to the other ring. Measure that length and subtract 16 inches (round up to the nearest cinch size) and you'll have a good estimate of your horse's correct cinch size.