Establishing the correct pattern size

Before the manufacturer can adjust a pattern, they must first select the starting pattern size to work from. North American manufacturers work on the premise that a size 40 pattern will fit a person whose chest measurement is 40 inches. Size 40 is the base size that manufacturers work from to create all other sizes afterward. The base size for European manufacturers is size 50, based on the premise that a person's chest will measure 100 cm (or half their chest will measure 50 cm).

When selling a suit off the rack, it is common to have to select a size that is larger or smaller than the customer's chest measurement if they have wider or narrower than average shoulders. When selling made-to-measure clothing, you will achieve the best results by working with the size that corresponds with their chest measurement, since the shoulders can be adjusted to fit the customer's requirements.

Body measurements vs. finished measurements.

Over the years various body measurement studies have been conducted to determine and document consistencies in the relationships between various body measurements. While there are differences between people from different countries or ethnic backgrounds, overall the method of comparing a person's body measurements to these recognized standard measurements works quite well in determining the adjustments required to the specs of a starting size pattern.

An average sized man will have a 6 inch difference between their chest and pant waist. This is why you will almost always find that a size 40 suit comes with a 34 pant. A person's stomach will usually measure 1 1/2 to 2 inches more than their pant waist. Since a jacket is buttoned over the stomach area, it is more important to observe the customer's stomach measurement rather than their pant waist when determining the finished coat waist measurement for a tailored jacket.

In order to arrive at a desired fit or style, a designer will add a certain amount of EASE to the standard body measurements assumed for a size 40 for example. By adding more or less ease, the garment will fit more trim or easy (loose). For now, we will define three different fit types as "Trim", "Comfortable", and "Easy". If you were to measure ONE back, side and front panel in the chest area as indicated by the dotted lines in the diagram below (and multiply by 2 to include the other half of the jacket), you will find that most comfortable-fitting North American made garments in size 40 will measure approximately 48 inches total. The total waist will often measure between 42-43 inches (for a 1/2 waist of 21 - 21 1/2"), and the half seat will measure approximately 1 1/2 inches more than the half waist.