Regarding the Coil Wrapping calculator:
How is Leg Length measured? it says “total per coil,” does this mean the sum of both legs on either end of a coil? where does the ‘leg’ start?
The leg length is the sum of both legs. The leg starts right where the coil exits the helix. Here is a very professionally drawn illustration of a coil, with a red line through the center.
So if both legs are the same length (as they usually are), measure one of the legs from the center of the helix to the point where the leg connects to the post in the atomizer. Then double that number.