Submitted by Judy
Most commercial patterns have an average cup size of a B or C, so you will most likely need to make a bust adjustment on a pattern. You can determine how large or small of an adjustment you should make by taking your bust measurement (across the apex of your breasts) and your high bust measurement (just below your armpits). The difference between these numbers tells you how much to adjust the bust area of a pattern.
Here is a great video that explains the measurements and how to make the adjustments: Full Bust Adjustment Tutorial
Hope that helps!