Ok, I looked around and could not find much on sizing however I came across this:
SM:less than 14.25"
MD:14.25 - 15.75"
LG:15.75 - 17.25"
XL:17.25 - 18.75"
Calf Measurements in inches around leg at mid-calf
**Recommend sizing down if between sizes
That being said, I got a large with my widest mid-calf measurment at 17", they fit great and would not want to go down one size as it would start to cut circulation at the top and bottom. The length is fine, ankle to back of knee. I had a stage 3 calf tear this year and am still recovering from it, I will be using these sleeves as long as the CW-X compression Pro leggings for the foreseeable future. Better safe than recurring either one again, good luck. Oh and I am 5'-11 and 190