Standard tuning
The bottom string or fourth string of the ukulele is tuned to a G. The third string is tuned to a C. The second string is tuned to an E. The top, or first string, is tuned to an A. – this is the same as putting a capo on the fifth fret of a guitar and only using the top four stings.
The ukulele’s string order (GCEA) is the same set of intervals as the top four strings on a guitar (DGBE), simply up a fourth!
A fourth merely means a space of four letters between notes. You count each letter including your beginning note to get your fourth, e.g A to D (A, B, C, D = four) - an A chord on a guitar is a D chord on a ukulele.