If you measure your horse in the winter be aware that hair can add an inch or more! I’ve found that typically the measurements you send in are the middle holes of the harness giving you a few holes smaller and a few holes larger. There are exceptions to that, for instance if you order from a less reputable seller.**You can either measure the horse or a harness that you’ve been using. If you measure a harness it’s best to lay it flat for the measuring, even unbuckling some of the buckles to get an accurate measurement.
When measuring the Horse:
A) Bridle: Measure from the corner of the mouth, over the poll to the other corner of mouth
B) Browband: Measure from behind the ear around the front of the head to behind the ear on the other side.
C) Noseband: Measure around the nose, two fingers below the prominent cheek bones.
D) Girth: Measure around the body behind the withers, where the saddle will sit.
E) Back Band: Measure from where the saddle would be, down the middle of the spine to the top of the tail.
F) Hip Strap: Measure from where the breeching will sit over the top of the rump to where the breeching will sit on the other side.
G) Breeching: Measure from the whorl just in front of the stifle on one side around the back of the rump to the whorl on the other side.
H) Breast Plate: Measure just behind the elbow around the chest to behind the elbow on the other side.
I) Neck Strap: Measure from where the top of the breast collar would sit, over the neck to where the breast collar would sit on the other side.
J) Traces: Measure even with the chest down the body to even with the rump. (DO NOT measure around to the middle of the chest and rump as you do when measuring for a blanket.) **Find out from the harness dealer if you need to add 12 inches to this number.
Here is a fantastic video that shows how to measure for a harness as well!