Here it is:

A) Measure from hand to hand (yes all the way)
B) Measure from bottom to top (again all the way) unless you do not want a small train, at which point from floor to nape plus 1"
C) now all the way around the largest part of your person plus at least 4"
D) Now how long you want each sleeve, plus 2"

Take measurement A and divide it in 4. *IF measurement A is LESS THAN C, divide C in 4*
But still keep A in quarters. That is your sleeve width and possibly your other panels width. If * then * is the measurement of your other panels

Cut%) Cut 4 rectangles that are A/4 by D. These will be your sleeves.
Cut#) Cut 4 rectangles that are B by either A/4 or C/4, depending on which you determined, this will be your body

Sew 2 cut% together on the short ends, sew the other 2 together.
Sew 2 cut# together from the top of a long side to what would be upper calf length on your person.
Sew the other cut#s at the top to each of the original cut#s, leaving about 4-8" in the center unstitched. Check to see which distance will fit about your neck more or less.

Match the top seam of cut% to the shoulder seam you have just made. Stitch 8" down on both sides.
Now sew the sides from the bottom up. Stop the seams 8" down from the last seam.

Cut a strip that you like the width of plus 1". make it long enough to go from mid-thigh around your neck back down to mid-thigh.
Now remember where you left part of the neckline unsewn? Cut the extra from each side. Sew this strip from mid-thigh to neck and back down and around again.

Hem the lot of it. If you are worried about it fitting around, you can always just make it wider by adding to measurement C

Here is a "how to" website, they also offer kimono fabric.

www.japanesekimono.com/kimono_fabric.htm