When I was still a teenager I read an article about choosing bra size. In short, measure under your bust, that is your band measurement then measure your full bust and for every inch difference add a cup size. Ok so I did this (I was about 18) under bust 28″, bust 32″. So that would be 28D, I thought I had it all wrong when I went to get fitted and they put me in a 32B.
When buying dresses they have bust waist and hip measurements, the bust measurement however is not the under bust measurement that is used for bras so if you wear a 32″ bra you probably need a 34″ or 36″ dress. It took years for me to realise this as I was in an Aus size 10 bra and size 10 dress (now resized down to an 8 ) and both had 32″ on them. The current dress sizes where the bust measurement is 2″ bigger than the measurement for a bra makes a lot more sense now I understand it.
If you look at a dress pattern, you will see that the measurement that the bust relates to in sewing is the upper bust measurement; this is taken under the arm not on the fullest part of the bust. For A and B cups there is minimal difference between the 2 measurements however if you are bigger this can be a problem. Off the rack clothing and patterns are generally designed for a B cup. So a garment that is a size 10 is for someone with a 34″ bust, 32″ under bust.
The same applies to knitting patterns.
If you choose your full bust measurement as your starting size you are making a garment that fits someone with your circumference but a B cup. If you are a B cup then you are in luck, you have the right size but for the rest of us the garment will not fit very well. The starting point needs to be what fits the rest of you and then add some width across the front only to cater for the bigger bust.
It took me years to work all this out. I kept getting advice to make a 36″ but I wear a size 8 (32″ bust), something didn’t measure up. If I put on a size 12 it hung loose like a sack, it was so big all over how could that be the size I was supposed to make? Oh well ignore all the advice and just make the size 8. If my clothes fit, my jumpers should and they did for a long time. I have since put on weight, this had led to me needing to work this stuff out because I can’t just make the smallest size and hope it isn’t too big any more.
This is what I have worked out.
High bust – use this to determine your general clothing size and starting size when making a top/sweater.
Full bust – use this to determine the number of stitches extra you need to add at the bust line. ie Difference between high bust and full bust needs to be added if you don’t want the ‘my sweater barely goes around me’ look.
Under bust – this is your bra band size.
Ease – this is the difference between the size of the pattern and the size the pattern was designed to fit. (Remember most are designed to fit a B cup).
I hope that makes sense.