Proper Suit Jacket Hem Length
The hem of a jacket can make or break the over-all aesthetic of a suit. If the suit has a perfect fit in the shoulders and arms, but body length is too short, it will simply appear too small, and the same goes for the opposite: if it is too long, it will appear too big.
In terms of proportion, the bottom of jacket hem should line up with the bottom line of the crotch, and this will vary, obviously, depending on the style of the pants.
A classic suit jacket will go with a classic style pant with a long rise. And a trendier jacket will pair with a trimmer pant which will have a shorter rise, and therefore the jacket will be slightly shorter than a classic, but still proportionate to the over-all look.
If you don’t have the perfect fitting pants with a comfortable preferred rise, then the following are two ways to determine the correct classic jacket length:
Cupping – With your arms comfortably relaxed at your sides, slightly cup the fingers around the hem of the jacket; which should fit perfectly in your hand “cup,” if not, then it’s an easy marker to determine if it is too long or not long enough.
Thumb knuckle – Again with your arms relaxed by your side, stand in front of a mirror, and if the middle of the thumb knuckle hits at the hemline of the jacket, then the length is correct.
*Obviously there are exceptions to every rule, and unusual arm length, either short or long, can make these two tests inaccurate.
Most sport coats follow the classic fit and length rule, and are typically worn with relaxed cotton trousers or denim with a long rise. Again, there are exceptions when a guy chooses a trendier appeal with fitted pants and jeans; the jacket tends to be more fitted and shorter in length.