I appreciate your answer. My horse doesn't match her height for most measurements though. The saddle is western, and a regular 32" pad is too long.
I think that a saddle pad must be measured first in relation to your horse!
10.2 to 13.3 : Pony Size (P/S)
13.3 to 15.3 : Cob Size (C/S)
15.3 to 16.3 : Full Size (F/S)
> 16.3 : Extra Full Size (XF/S)
I think for your saddle, I think a 28" long saddle pad is long enough for a 26" saddle. But, you must like it too, if you think that a saddle pad a little longer would fit better, takes bigger.
I hope this helps, bye.