Let’s learn how to measure the sleeve cap correctly. We already spoke about the cap height, now it’s time for the cap width for the best fitting sleeve for your body type!

A good starting point for determining your cap width for a blouse sleeve pattern can be found using this method:

Measuring Sleeve Cap Width – Step-by-Step

1. Put your muslin/toile on. (I used a sleeveless dress so it would be easier to see the simulation.)
2. Sew a piece of elastic together and place it on the bicep area, aligning it to the bottom of your armhole when the arm is relaxed. (Check the position in the mirror.)
3. Mark about 2–3” down from your shoulder tip and remember that measurement for marking your pattern.
4. Mark off your across-back area at around that same height.
5. Place a piece of tape on the end of a measuring tape and tape it to the across-back areas.
6. Then wrap it around to the across-front.
7. When the arm is relaxed, you get a shorter measurement. (This could work for knit tops.)
8. As you lift the arm up, the measurement increases. This measurement is a good starting point for woven blouses/tops.

This is a great method for customizing your sleeve patterns for the best fit. Make sure you always make a muslin after you draft your flat pattern. Never skip that step. It’s the only way of checking the fit, as you might never get it right straight from the flat pattern.

This information and more can be found in The Fitting Book. Order your book today through the link below.