That it's why I wrote the free Android app "Vaper's Toolbox". It will figure out how much wire to use for both Kanthal and Nichrome.
That was you? I love you.

For your viewing pleasure:Please do not use anything except Kanthal (I prefer A1 but other grades will work fine) or Nichrome for your atomizer.
Something like guitar wire is either steel or, if you're really classy, silver.It's low resistance wire, and not made for atomizers. The coating to preserve the wire is unknown, and regardless of that when you wind a coil you'll be making a sub-ohm coil whether you want to or not!
While there are other resistance wires, Kanthal and Nichrome are proven. Some dislike the idea of chromium wire and use only Kanthal, but I don't think anybody's ever found any leaching chromium in a dangerous form from Nichrome.
Kanthal is quite cheap in hundred foot sections on Amazon or eBay.
Please note that I'm an old fuddy-duddy that still likes the old-fashioned micro-coils that we used to use back in the day. You know, 2013?