Something approximately like this: One needs to make sure the coil is wound tightly with no gaps or overlaps, which can get tricky for a thin wire. If it is the same size as the 42, it's most likely a set of 9-42's. We've broken down the first three categories by our most popular instruments: Acoustic Guitar, Electric Guitar and Electric Bass Guitar. There is an easy way to measure wire diameter. Wind the wire tightly around some cylindrical object, measure the length of the coil and divide by the number of turns. Acoustic Guitar String Set Gauges “extra light":.010 .014 .023 .030 .039 .047 "custom light":.011 .015 .023 .032 .042 .052 "light":.012 .016 .025 .032 .042 .054 "medium":.013 .017 .026 .035 .045 .056 "heavy":.014 .018 .027 .039 .049 .059; Acoustic Guitar … Remove the existing strings. The first thing that needs to be done, once you have your tools ready, is … If you strung them right in the first place, you should be turning the tuners for the bass strings (the three largest and closest strings to you) and the treble strings (the three thinner strings furthest away from you) to the right to loosen the strings. i have to replace my strings on my guitar for the first time, i like the factory strings, but how can i tell what gauge they are? See if you can buy single strings. If you can, buy a 42 and a 46 gauge. Compare the low string to those two separate strings. Start out by loosening ALL of the strings. Just click on the instrument or image you are interested in to get more information and see what strings we suggest.