There is not a certain number to measure good or bad DOH (days inventory on hand), because each company has its own accounting period, and each industry has its own special feature. For dairy products, 7 days of DOH is too long, but if it is for airplanes, ship manufacturers’ 7 months DOH is probably normal for them.

The rule of thumb is that the lower of DOH the better. The fewer days you have inventory on hand means you have less capital tied up on products. You also use less warehouse space, and fewer laborers to move these products around.