Kiln seasoning reduces the moisture content of timber far more rapidly than natural air drying, typically completing in rather than years. While the traditional rule for air drying is "one year per inch of thickness," kiln drying for 1-inch boards often takes only 2 to 14 days . Typical Kiln Drying Times by Species
Here is a breakdown of the factors determining kiln time, based on general wood science literature: kiln seasoning time for timber