Things You'll Need
While tree sizes vary from brand to brand, a narrow tree is generally indicated by a dot-to-dot measurement of 4 inches or less, a regular tree by a dot-to-dot measurement of 4.25 inches and a wide tree by a dot-to-dot measurement of 4.5 inches or more.
English saddles are expensive, and if you know how to measure them properly, you have a much better chance of finding a used one that will fit you and your horse properly. The biggest mistake most people make when measuring a saddle, whether they are buying or selling, is to measure only the seat size. While it's true that the seat size is the only standard measurement from one saddle brand to another, you can use the measuring instructions listed below to measure an English saddle for seat size, flap length and tree width--regardless of the saddle brand.
Set the saddle on a saddle rack with the seat facing up. Locate the pommel of the saddle. The pommel is the raised, center point at the front of your saddle.
There are nailheads on both sides of the pommel. Oftentimes, the nailheads on an English saddle will be engraved with the brand name of the saddle. Choose one nailhead and measure in a straight line from the center of the nailhead to the center of the back of your saddle, called the cantle. This measurement represents the seat size; it should be in half-inch increments.
Lift the skirt of your saddle (the half-circle of leather coming off of the pommel) to reveal the metal stirrup bar. Measure straight down from the center of the stirrup bar to the bottom of the saddle flap to determine flap length.
Lay the saddle upside down on a towel so that the cantle is touching the floor and the bottom of the saddle is exposed. The strip of unpadded leather running down the center of your saddle is called the gullet. On either side of the gullet you will find the panels of your saddle. On the front of each panel there are four felt dots. Measure the distance between the two felt dots closest to the gullet. This is your "dot-to-dot" measurement, which gives an accurate representation of your English saddle tree width, regardless of saddle brand.