Many knitting patterns include a small amount of shoulder slope shaping in their instructions. It's a very difficult measurement to take accurately on the body. The greater the slope, the more important it becomes to get an accurate measurement because a larger slope impacts the fit of your garments more.
Take a piece of paper towel. My sample is 11" by 12". Look at my photos below for reference. All lines that will be marked should be kept square. Cut out a neckline with a 3" drop. You can curve this like a crew neckline at the bottom. Mark in a shoulder seam with a pen. Line that up on your body, flush against the base of your neck with the shoulder seam in position along the top of your shoulder. Mark your shoulder line with a pen. Find your vertical outside shoulder line by locating the knobby little bone behind your shoulder, it's about 2" below where a shoulder/sleeve seam would be. I use my index finger hooked over my shoulder from the front to line up where my shoulder edge should be. Draw a line down and trim away the excess. Put the paper towel back in place aligning the neckline edge, and outside shoulder edge. Push the bottom outside corner up until it is visually square, then pinch the outside edge at the top of your arm and pin out the excess. Take it off and draw a line from the neck edge to the shoulder edge. Pin along this line and check for accuracy. You can now measure your shoulder slope and mark in a line from the outside edge to the neck edge. My slope is 3/4", a little less than average. To get an accurate slope I would multiply my row gauge by my personal slope and then work my shoulder castoffs or short rows accordingly. There will be some rounding depending on row gauge as there always is in knitting. As an example, with a row gauge of 7 rows per inch. 7 x .75 = 5.25, I would work my shoulder shaping over 6 rows. If I had a more sloped shoulder of 1.25 inches with a row gauge of 7 rows per inch. 7 x 1.25 = 8.75, I would work my shoulder shaping over 8 rows. Keep in mind that the wider the neckline of your garment the less important shoulder slope becomes.
|Note the pin at the right side.|
|I've drawn in the shoulder slope in this photo|