Blanket Fitting
Below are some "rules-of-thumb" for blanket fitting.
68" - For 1 to 2-year Old
(13 1/2 to 14 hands tall)

72" - For 2-Year-Old-Horse
(14 1/2 to 15 hands tall)

76" - For Average Horse
(15 1/2 to 16 hands tall)

80" - For Large Horse
(16 1/2 to 17 hands tall)

Hint: Measure from The Middle of the Chest (around the side) to the Middle of the Rear. (order next larger size)