For the ukulele to sound right, its four strings must be in tune. That is, the open strings, when plucked, must sound as in the desired tuning.

String sound sound file linear tuning sound file reentrant tuning
1 A
2 E
3 C
4 G

The sound files above reproduce the sounds of the C6 tuning of an ukulele. You can play them here and set the strings accordingly by ear. Of course, this is only possible when you are online … The following options are much more convenient and reliable:

A clip tuner measures the sounds of an ukulele electronically and displays the deviation of the measured tones from the standard tone. Some devices have their own setting for ukuleles (usually marked „U“) and then only recognize the tones A, E, C and G. It is better to use the setting for chromatic mode („C“ = semitones), because then the actual sounds will be displayed.

Clip tuners are available in different price ranges between approx. 5 and 50 euros. Some devices react to the vibrations of the ukulele, others have a built-in microphone and record the sound waves.

The advantage of a clip tuner is that you can tune very accurately and easily recognize deviations. The disadvantage is that they need (battery) power and that your hearing is not trained.

There are many applications for smartphones that mimic a tuning device. The sound of the ukulele is recorded with the built-in microphone. The apps then show you which sound is registered and how much it deviates from the sound you are looking for. Examples are TuneWave (iOS) or Guitar Tuna (Android).

Tuning with these apps is not quite as easy as with a clip tuner, but it's handy.

A tuning fork usually resonates in the pitch of A and can therefore be used excellently to tune the 1st string of an ukulele. From there you can tune all other strings as well. How this works is described in detail here.

In C tuning (g, c, e, a) you tune the first string A with the tuning fork (in D tuning tune the fourth string A first). Holding the tuning fork by its base, strike the tines of the fork sharply on your knee and immediately place the base of the tuning fork on the body of the ukulele. The vibration of the tuning fork will transfer to the ukulele and an A tone will be emitted. Hum the A tone and put it in your ears and mind. Now pick the A string on your ukulele and bring it into tune with the A tone you are humming. Once you have tuned your A string to the tuning fork, find and fret the other A notes on the other three strings and tune those A notes to the A in-tune A string.

Jim D'Ville: „Learning to Play Ukulele by Ear“ (Ukulele Yes! 08:01 (2009)

Jim D'Ville: Tuning The Ukulele By Ear (2007)

The advantage of a tuning fork is that it does not require power. The disadvantage is that you have to adjust all other sounds by ear.