HOW LONG SHOULD A PROPER SUIT JACKET BE AND HOW DO YOU DETERMINE THE PROPER LENGTH?
The hem of a proper suit jacket should fall to the top curve of your buttocks. If the hem stops on top of your buttocks, it is too short. If it falls all the way to the bottom entirely, it is too long.
Another easy way to determine proper length is using your hands. Hold your hands by your side, completely relaxed, and see if the hem of the jacket stops middle of your hand. If it does, then that is the ideal length.
Finally, the most accurate way to measure a jacket’s proper length is to see if it falls between the knuckle of your thumb and the joint above it (the carpometacarpal joint, if you want to be technical about it).