Measuring for Width: Simply measure your unshod horse's hoof at the widest point.
Measuring for Length: Measure from the toe to the buttress line. The definition of buttress changes from farrier to hoof boot manufacturer, so what you really want to make sure you're measuring is the weight-bearing wall of your horse's hoof. We have a diagram included in our Measuring Guide (linked below), but the most important thing here is that you want to make sure you do not include the heel bulbs in your measurement. If it helps to visualize, imagine painting the bottom of your horse's hoof and then stamping it on the ground. You are measuring what that imprint would be.
Analyzing your measurements: Once you feel confident in your measurements, there are a few important questions:
Are your measurements the same, or nearly the same? If so, we recommend the Cavallo Regular Sole Styles and most EasyCare EasyBoot Styles.
Is the Length longer than the Width? If so, we recommend the Cavallo Slim Sole Styles (for horses whose hooves are 1/4" - 1/2" longer) and most EasyCare EasyBoot Styles
Is the Width longer than the Length? If so, unfortunately, we do not recommend any hoof boot styles for your horse.