Price is per foot, with a minimum order of 10 feet. Adjust "Quantity" to select how many feet you need.
Litz wire (from the German "woven") is made of individually insulated magnetic wires woven into a pattern that equalizes currents through each individual strand.
At higher frequencies, current prefers to travel around the outside of wires (called the skin effect), so having a bundle of smaller wires is better than a single thicker wire. The smaller wires are then woven together in a pattern that ensures each wire spends an equal amount of time at every location across the cross-sectional area of the bundle, which has the effect of equalizing currents through each strand of wire. For these reasons, Litz wire is the best design for high-frequency applications.
To determine the length of wire needed for winding coils, the required wire length is the number of turns * πD, then add about a foot for two 6" wire leads (or however much you need).
Also take into account that for each full set of windings, the diameter of the next winding will increase by twice the thickness of the wire. So if a coil allows 25 turns before the wire must be doubled back over the existing windings, and the wire diameter is 1/16", then the overall coil diameter becomes 2 x 1/16" or 1/8" larger. For example if you have a 3/4" coil diameter, need 50 turns, and the coil can handle 25 windings per layer:
the first 25 turns around the 3/4" diameter coil requires (25 x 3.14 x 0.75) = 59 inches of wire
for the second 25 turns the diameter is increased 1/8" for 7/8" diameter which requires (25 x 3.14 x 0.875) = 69 inches of wire
then add 12" (or whatever you need) for the leads, and the total length is 140 inches, or about 12 feet.