Magnet wire is insulated copper wire and the ohms per thousand feet is normally measured at 20? C or 68? Fahrenheit. 42 gauge magnet wire has 1,659 ohms per 1,000 feet of magnet wire at 20? or 68? F.

Note: 1,659 ohms is the same as 1.659 K ohms

1,000 feet of 42 AWG magnet = 1,659 ohms nominal at 20? C or 68 ? F.

If the temperature of the magnet wire is 25? C or 77? F, I multiply 1,659 (ohms per 1,000 feet) by 1.0197 (Factor) and get 1,692 DC ohms which is an increase of 33 ohms due to the increase in temperature.

Another way of doing it is: If your magnet wire measure 1,692 ohms per 1,000 feet at 77? F. you then divide by the conversion factor which is 1.0197, this will give you the nominal ohms at 68? F by which most magnet wire manufacturers use as a standard.

This may be confusing to most players using pickups but it is helpful in rewinding and manufacturing. I use this conversion all the time to determine exactly what gauge of magnet wire I am using or what’s used on a vintage pickup. The conversion chart below can be used with any magnet wire to determine what the actual gauge is at the nominal 68? F or 20? C.

Note: to measure 1,000 feet of magnet wire sounds difficult but I use a digital meter and measure 10′ (feet) and multiply the number by 100 to get ohms per 1,000 feet. Once I determine what that number is. I measure the room temperature and use the conversion chart. The number I end up with is the actual ohms per 1,000 feet at 20? C or 68? F.

If a pickup has 6.636 K ohms, the pickup has 4,000 feet of magnet wire.

Example: 1,000 feet of 42 gauge of magnet wire at 68? F equals 1,659 ohms X (multiply) 4 (= 4,000 feet of magnet wire) = 6,636 ohms or 6.636 K ohms.

Conversion Chart for Magnet Wire: