The notes on a 4 string bass guitar are the same as a regular 6 string guitar, but the bass is missing 2 strings (B string and high E string). We included a attachment below showing all the notes on 4 string bass.
The fastest way to learn your notes is to memorize the 12 notes on Low E String then move on to the 3, 2, 1 strings. Example on the 4th E string 5th fret is the note (A) and on the open 3rd (A string) is also the note A.

Notice the notes start over at the 12th fret? |