The baritone ukulele measures 30 inches in length, compared with the smallest ukulele, the soprano, which measures 21 inches. The larger size creates a much deeper tone than other ukuleles, with a sound closer to the guitar than the high pitch of traditional ukuleles.
The tuning and chords of a baritone also differ from other ukuleles as well. Though the standard tuning on a soprano or tenor ukulele is "GCEA", a baritone is tuned to "DGBE", which, not coincidentally, is the same tuning as the top four strings on a guitar. The longer neck and body of the baritone require special, heavier nylon strings to help create its unique, deep tone.
Another side effect of the longer neck and different tuning is that it changes the positioning of the chords as well. The three extra frets on the baritone mean that chords typically used on a standard ukulele, the soprano, will be three keys lower on the baritone. For example, the chords for a "G" on the soprano will be the chords for a "D" on the baritone.
Because of its size and sound proximity to the guitar, the baritone ukulele is often used as a starter instrument for beginning guitar. The heavy and deep sound also make the baritone ukulele the most logical choice for bass ukulele in recordings and live performances.
Though the ukulele is most commonly known as a small instrument with a high tone, the baritone ukulele is sought for the exact opposite reason. The baritone is not as widely available as other ukuleles, but among ukulele enthusiasts, it is fairly common.