Circumference of the Sleeves
No matter what type of garment you are making, the circumference of the sleeves has to be precise in order to achieve the right fit and get the proper range of motion. While it is true that the length and style of each sleeve will vary and will affect the amount of ease that you get, a general rule of thumb is to measure a minimum of 2 inches above the circumference of the bicep. However, do keep in mind that if you are making a coat or a jacket, you’re going to be wearing layers underneath it, so if you want to get a comfortable fit, you’ll want to have more than 2 inches of ease; 4 inches is recommended. To do this, measure the circumference of the bicep at the fullest point and match it to the pattern.
Length of the Sleeves
Believe it or not, the length of the sleeve can have a big impact on the fit and feel of the garment; yes, even up near the armhole openings. To ensure that your sleeves are fitted properly, you are going to want to make sure that they are the proper length for your body. If the sleeves are too long or too short, there’s no doubt about it: you’re going to be uncomfortable.