Measuring for rugs

[clarabella_78]

Hi,
I've been looking at horse rugs on ebay (my other favourite site) - how do you know which size is right for you horse, e.g. a 5'9 rug - which measurement does this refer to?

 

[Tots N Dots]

if you get a tape measure and measure from the centre of the chest to the back of the bottom where you want the rug to end. would be equivilent to the measurement fron the front chest buckle on the rug to the bit where the fillet string would be at the back.
if that makes any sense?
found this if it helps?
Picture of how to measure for a rug