This gives the ohms per length so whether you microcoil or use standard coils you will know the approximate ohms made
I take a 10cm length, make my coil and cut the same length of each leg left over
If it is 0.20 and I take 3cm off the legs I know my coil will be about 1.7ohm
If you have an android phone/tablet or use an emulator you can use Vapers Toolbox it'll work out single/dual/quad and has other useful info like how many raps to the coil diameter also an Power tool to work out amps.