We sell our C7 and C9 light strings in two lengths: 10-socket and 25-socket.
All 25-socket light strings are 26.5 feet (~8 meters) total
All 10-socket light strings are 11.5 feet (~3.5 meters) total
All light strings, regardless of socket count, have an 18 inch (~0.5 meter) length of wire from the plug to the first socket. The sockets are spaced 12 inches (~0.3 meters) apart, and there’s another 12 inches of wire leading to the female plug on the end of the light string.