Choosing the right size to make is one of the most important things you can do.
If you have a large bust and choose a size using that measurement it is unlikely you will get a good fit in the neckline and shoulders, and that area will end up being oversized. For Experimental Space patterns, choose the size based on your high bust measurement.
Full Bust: What you would normally think of as just ‘bust’. It is the measurement around the largest part of your chest.
High Bust: This is the measurement around your body, directly under your underarms.
The patterns allow for up to a +2.5″ difference between high and full bust. (i.e. High bust of 35″ and full bust of 37.5″ could make the 35″ pattern without any adjustments) For the best fit, if your high/full bust difference is bigger than 2.5″, do a FBA (or short rows if knitting) to give you the fabric you need at the bust. This way the shoulders, neckline and bust will all fit perfectly.
If you do not have a large bust and clothes normally fit you without having to size up for your chest then you can just use your high bust measurement when choosing a size. If your high/full bust difference is 2.5″ or less, no adjustments are needed.
If you have a large bust you might find you typically have to size up in clothing to get it to fit over your chest. When you make your own clothing, the better way to do this is to make the size your shoulders and neckline need (i.e. the size based off your High Bust) and then do an adjustment for your Full Bust. This means your shoulders and neckline will fit perfectly because they haven’t been made larger to account for a bigger bust. In this case, you would do a FBA (Full Bust Adjustment) which is usually straightforward and will not change your neckline or sleeve size.
Now that you’ve chosen the proper size to make sure the neckline, shoulders and bust sized properly you are on the right track to a successful fit!