An ill-fitting coat is not only uncomfortable but can take away from the overall clean look of a good suit or tuxedo. Measuring proper coat size is usually a two-person project to ensure accurate measurements.
Put on your dress shirt, socks and trousers. Stand against the wall with your feet flat. Have the other person mark on the wall (with a pencil) where the top of your head is. Measure from the mark to the floor. This measurement determines whether you need a regular, tall, short or big coat.
Regular is someone with equal chest and hips measurement that’s 5 feet, 8 inches tall to 6 feet, 1/2 inch tall. Tall is someone who is between 6 feet, 1 inch and 6 feet, 3 inches tall. Short is someone who is 5 feet, 3 inches tall to 5 feet, 7.5 inches tall. Big is someone with a less athletic profile between 5 feet, 8 inches tall and 6 feet, 1/2 inch tall.
Raise your arms slightly and have the other person measure around just under your arms, making sure to cross over the shoulder blades and the fullest part of the chest. Coat size is equal to your chest size (for example, if your chest is 38 inches, your coat should be a size 38 regular, tall, short or big, depending on your height).
Put your arms down and measure around your chest and fullest part of your arms (most prominent part of bicep). If this measurement is 7 or more inches larger than your chest measurement, get the next larger size coat to keep from binding the upper arm and shoulder area.