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Some breeds will continue to grow well beyond 2 years. The heavy breeds and even the Arab will grow until they are about 4 or 5. A QH can grow until they are ~4 but their growing slows down severely at about 2 1/2 or 3. If your horse is 14h 1 at 2 then you have a shot at 14h 3 but should at least get to 14h 2.
This is a fairly good method of estimating your horse's finished height: http://www.ultimatehorsesite.com/inf...ngtesting.html