How to Adjust Shoulder Width for Better Fitting Sweaters

Armhole shaping decreases for garments are normally calculated by subtracting the cross shoulder measurement from the cross back or cross front measurement, dividing that number in half and then plotting a curved underarm. As an aside, the back cross shoulder measurement above the armhole is larger on most people than the cross front one. This is the case even on well endowed figures, partially due to the natural curve of the upper back above the shoulder blades. In my case the difference is one inch bigger at the back. I use the smaller measurement from my front to calculate the armhole and count on ease and the stretch created by the weight of the sleeves to pull the back into the correct position. If I was not working with a knit fabric this would not be an option. If I had a larger difference I would assess if the stretch would be enough by testing the amount of stretch on the lower part of the back once I had knit about six inches or so. It is important to evaluate this as some patterns will distort if they are stretched too far. Another option would be to split the difference and perhaps knit the front a little wider than your real measurement. It's always a situation of matching the individuals shape with the necessary adjustments.

The shaping of the armhole is usually worked over one and one half to three inches of length. Depending on your shape and height this may be too quickly or too slow a rate of decrease. Different designers use different standards as to how they start these cast offs. Some start with an initial cast of one half to one inch and then decrease in multiples two more times before doing single decreases until they get to the right number. If the shoulder measurement is too wide to begin with or you have picked your size based on a fuller than B cup measurement it is likely that this area will fit poorly. The depth of the armhole is generally one to two inches longer than your actual armhole depth measurement. (See my post on sleeve caps here to find out how to measure this accurately). The standard used most often for both patterns and retail, is at the higher end because too long and you can wear it, too short and you can’t.

To customize the fit for yourself take the one half body measurement, subtract the cross shoulder and divide by two. As an example (20 - 14 = 6) divided by 2 = 3. The simplest way to work out the decreasing required is to use knitting graph paper. This is graph paper with rectangles that accurately reflect stitch gauge instead of squares. You can find it here.  Draw in the underarm horizontal line  and the armhole vertical line, and then add a curve on the graph to join them and draw in the decreases working on every other row. You can also cut the shaping out on paper, (If you are using real size knitters graph paper), tuck it under your arm and check the mirror to ensure you are happy with how the curve hugs your underarm. You may need to make the curve start sooner and end higher for your body. I've shown two curves in my sample to give you and idea of how this might work for you. 


The sleeve cap will also need to be adjusted to fit into the new armhole. Refer to this posting for details on how to change the cap.