The bass guitar is founded on electric guitar technology, so its not surprising that its strings share the same basic materials - nickel-alloy, nickel-steel and stainless steel. As with the guitar, roundwound strings are generally favoured by rock players, while jazz players often use flatwound strings, particularly on fretless basses.
Again, sets vary a little between manufacturers, but the chart below gives a general picture:
4-string
5-string
G
D
A
E
B
Extra-Light
.040
.055
.075
.095
.128
Light
.040
.060
.080
.100
.128
Medium Light
.045
.065
.085
.105
.130
Medium
.048
.067
.085
.106
.130
Heavy
.050
.070
.090
.110
.135
As with all strings, theres a trade-off between tone/volume and playability - heavier strings sound better but can be harder to play, especially for beginners.
