I've been doing some research on scoggers since they were knit to go with my later period kirtles. The descriptions I've read have said they were plain knit from "just above the elbow to the wrist." So, using those measurements, I composed a "quick and dirty formula for making scoggers." The important part in this project is the gauge of your knitting. So be sure to do a true 4"x4" swatch to get your rows and stitches per inch. If this gauge isn't on, then your scoggers will either be too tight or too loose.
Upper arm measurement:
(I used about 3" from my elbow, which I found to be good so that the scogger doesn't slip off your elbow)
Measurement of wrist:
(make it a tad loose if you tend to cast off tightly like I do)
Measurement from upper arm to wrist with elbow bent at a 90° angle:
Then calculate how many stitches per inch you get. Multiply this by the measurement for your upper measurement and for your wrist measurement.
Then calculate how many rows per inch you get and multiply this by your "arm to wrist" measurement. This will be how many rows long your scogger will be.
Now subtract the lower stitches from your upper stitches. This will be the number of stitches that you need to decrease throughout your scogger. Divide this number into your rows to know how many rows to decrease your stitches. For my scoggers I found 1 decrase per every 2 rows was perfect, but I have very small wrists (6") and, um, curvacious upper arms.
Upper arm: 14"
Gauge: 4"x4" = 20 rows x 16 stitches on size 10 (6mm) needles
So I cast on: 57 stitches (I'll explain that in a minute)
Needed to cast off to 25 stitches
Need to cast off a total of: 32 stitches over 75 rows, so almost 1 stitch every other row.
I also added 3 rows of moss stitch (seed stitch) at the top and bottom. The only thing I would do differently would be to make the top measurement an inch or so smaller so that it isn't as loose. I will do that when I make the ones out of the Merino wool I just got in.
I'll try to get photos posted this afternoon.