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This is my calculator, it's not perfect, but it's better than most things out there.
It will calculate a rough number of bights for a square turks head knot (diameter and length are the same roughly) based on the width to cover as well as the minimum length of string to cover the knot at roughly 45 degrees. Less bights will be a shallower angle, more bights will be more acute and taller. In general this form of turk's head is near an aspect ratio of 1:1 so 1" high, near 1" diameter, or .75" x .75 diameter but the foundation length will be a rough function of PI. If you don't have the length of the foundation take the diameter * pi will give you the circumference. The area (Length x Heigth) plus 20% overlap will give you the general amount of string at 45 (You have 2 layers and square root of 2 is the diagonal of the intersections for covering the area at 45) if you use more bights the attack angle will be higher, if you use fewer bights the knot will be shorter) If you need to know long versions of this knot, odd numbers of wraps, 3,5,7,9, each will add one unit of height and double the length in the calculation. and even wraps works for odd turks head bight counts and this calculator doesn't really cover tha calculation but will give you a general idea of length. (This is for even calculation of square 1x1 ish knots).
Scarf slide project double check on the calculator:
8 oz (8/64th or 1/8") Vegtable tanned Horween Horse Butt 1" wide beveled strip 3 1/64" long soaked thru, wet formed with a scrap to buffer the rubber band lines, slid onto a bic lighter to oval shape it out overnight.
Lace used was 3/32" Beveled veg tanned kangaroo, knot is 18 Bight x 19 Lead Calculated 22 Bight but It snugged down too tight as I worked it. It's a single strand 85" long (started at 113" string) left over was enough to do 22 bight suggested by the formula above. So the double check was pretty good overall.
For 2 tone I'd suggest 10 bight in two passes or pineapple for a slide this size.
in 1/4" beveled veg tanned cowhide lace it suggests 10 bight, this ended up 8 bight where it firmed up a bit too much to keep adding bights Likely I needed to keep it a bit looser as well, about 30" overall consumed, but with 10 it would have been very very close too. I started with about a meter of lace
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