Ukuleles traditionally have four strings, and the most common tuning is G-C-A-E (also called the C or C6 tuning and sometimes just the G tuning). The first G string can be low or high (an octave difference). The latter, or high-G, is called 're-entrant' tuning and is the original tuning. Many players who came to the uke from the guitar prefer low-G, however. The strings are tuned like the first four strings of a guitar with a capo at the fifth fret.
The string notes are D-G-B-E for baritone ukes (guitar players will be familiar with that tuning since it's the same as the guitar's first four strings). This is also an alternate tuning for tenor ukes.
Gettuned.com shows how standard tuning works with a piano (the A is the first string, E the second, C the third and G the fourth):
This is, of course, re-entrant of high-G tuning. If you use a low-G tuning, the proper note in the above diagram would be the third white key to the left of the C.
They also have an online uke tuner (baritone sounds have to be individually selected, however). There are some variant tunings on Uke Hunt, along with sound clips. Flea Market Music has another tuner, but re-entrant C tuning only, no baritone or low-G. Others are available online.
Alternate tunings have been popular in the past, particularly A-D-F#-B (called D or D6 tuning, a whole tone or step higher than the C/G tuning) and even E-A-C#F# and Bb-Eb-G-C. You'll see a lot of these tunings on vintage song sheets, but whether anyone used them or simply played in the current standard tuning I can't say.
The Kala Pocket Ukulele, a sopranino, is tuned like a baritone (D-G-B-E) but an octave higher. Sometimes tenor ukes are tuned to D-G-B-E but to do so requires a different string set from the standard C tuning.
The A-D-F#-B tuning is still used as the default in some areas, including Canada's east coast and some parts of Europe. It was the default tuning for the Chalmers Doane Ukuleles in the Classroom program in Canada, too. Others are seldom seen outside vintage song sheets today.
The late John King and Jim Tranquada, writing in The Hawaiian Journal of History Vol. 37 (2003), noted that C6 tuning appears in the first published ukulele method book, written by Ernest Ka'ai in 1910. But although C6 dominated music publishing, Vaudeville and music hall performers often preferred D6 for its somewhat better projection. This was also the preferred tuning of both Roy Smeck and George Formby (from Ukulele Yes e-mag).
The above paragraph is reduced from an interesting comment in Ukuleles Yes, on the Internet's pervasive ability to homogenize things and make the C/G tuning the most prevalent. It's like American English: widespread use of the Net along with Microsoft, Apple and other American-made computer products, make it hard to keep British English in the fore. D6 tuning may not die out, but it will be hard pressed to retain its followers when more and more players use C6 in jams, songs, chord books, etc.
Here's a good page that explains some popular tunings from Southcoast Ukes. the author notes, "There are two keys below the key of C: B flat & A, that have been lately ignored for some unknown reason. They are excellent options on any instrument larger than a Soprano body - traditional or long scale. That icon of the jazz era, Ukulele Ike generally used these two tunings with his solo work. He played them on a standard 15” scale concert uke to beautiful effect, producing a mellower tone than the sharp sound on a C or D tuned Soprano. He used the prevalent gut string material of the day, and in doing so developed a unique playing style (see further discussion on the “Heavy Gauge Ukulele Strings” page)."
Many uke string sets are designed to be used for either C/G or D/A tuning, but you will need a different set of strings to get the E tuning and others (you can use nylon guitar strings of the appropriate diameter).
Uke strings are tuned like the higher four strings on a guitar; the same relationship between strings, except five frets higher. Those same strings on a guitar are tuned D-G-B-E (just like a baritone uke - this is also known as "Chicago tuning" on tenor guitars and other instruments). Put a capo on the fifth fret of a guitar and you get soprano, concert and tenor uke tuning: G-C-E-A (or on the seventh fret for A-D-F#-B tuning).
However, the traditional uke is tuned with the fourth (G) string an octave higher. This is called re-entrant tuning. So it's the same note (G), just higher and brighter. That creates the popular My-Dog-Has-Fleas tune when strummed from the top down.
Low G on soprano ukes may require a wound fourth string, however. James Hill writes in Ukulele Yes e-zine that: "...my recent experience has convinced me that Low-4th tuning doesn't work on soprano-sized instruments unless a wound 4th string is used (recommended gauge is between 0.026" and 0.030"). The nylon low-4th string works in D6 tuning because the tension on the 4th string is higher. In Sheshatshiu, I opted to teach in high-4th tuning because ArtsCan Circle had already established the use of C6 tuning in their programs, because high-4th tuning tends to be a more "forgiving" tuning for beginners and because I didn't have any wound strings with me."
Baritone ukes are tuned D-G-B-E (called G tuning), like a guitar (which sometimes causes their critics to belittle them as tenor guitars). Baritone ukes usually are low-D but there are some high-D string sets available. For re-entrant baritone tuning, you can use a classical guitar string (first or high E string). There are also sets of strings to tune a baritone G-C-E-A. I prefer to play it in its original G (or re-entrant G) tuning because the C tuning makes for very tight, stiff strings that I find hard on my fingers, and the pitch seems too high for the body size.
If you're a guitar player new to the uke, you can play the same guitar chords and finger picking patterns on a uke, but the high-G string creates a different sort of sound. You have to change some of your patterns if you use bass runs or particular finger picking patterns, but it's easy to get accustomed to playing a uke coming from a guitar. You may even find that, with only four strings to contend with, you're a better uke player than a guitar player!
You can also string a uke in low-G tuning, so it has a bass note in the fourth string, not a high note. This makes it even more guitar-like for chords and picking patterns. Some songs definitely work better in low-G, but others are best in high-G. Personally, I like both, but I tend to play my high-G ukes more because I prefer the sound and it makes the uke different from a guitar. But you should have both on hand. It's a good excuse to own another uke!
Eight string ukes are tuned like a normal uke - GCEA - but the second set has some differences. The G pair is an octave apart - high and low G together. So is the C pair. The E and A pair are tuned to the same pitch. This is usually written gGcCEEAA to indicate the octave difference with upper and lowercase. However, some players prefer to tune one or all pairs to the same note, not an octave apart.
Six string ukes have paired C and A strings. The A pair are the same note, but the C pair are an octave apart (low and high C). Again like the eight-string, players can tune either or both pairs to the same note or an octave apart. You can also choose high or low G.
Five-string ukes have a paired G string, usually tuned an octave apart.
I personally think the octave difference on the multi-string ukes really makes the instrument sound beautiful and distinct, but it's up to you what you want it to sound like.
The Guitalele and the U-tar have six strings laid out like a guitar, not in pairs. They are tuned like guitars capoed at the fifth fret: ADGCEA. They are really short-scale guitars and, despite the names, not ukuleles.
Bass ukuleles are tuned like guitar basses at the same pitch: E-A-D-G.
If you're interested in a more technical perspective read the page on "Tunings for the tenor ukulele" by Kawika Ukuleles.
Tuning is critical. And thanks to modern technology, you can buy a simple, clip-on, battery powered uke-specific tuner for $10-$20. That sure beats trying to tune with a pitch pipe (how 20th century!) or even a tuning fork. You can buy a ukulele-specific tuner, or a chromatic tuner that can be used with several instruments. Some have both a clip-on (vibration) tuner and a microphone for tuning off the instrument. Kala, Pono and Lanikai have a branded tuner they sell with their ukes.
My current favourite is a Snark clip-on tuner. I find it more sensitive than any other clip-on I've used and works with bass and banjo ukes where other clip-ons did not. It has a bright light, big face, fully-pivoting head and easy-to-read dial. The most commonly used model in the uke community is the guitar-bass clip-on, but the all-instrument model has a tiny microphone as well as a clip-on, which can be useful for instruments with low vibration. These can also be bought online for much lower than the suggested retail price.
I've also used a Profile PT-2900, which is chromatic, ukulele, guitar, violin and bass tuners combined in a small, clip-on device (it's the oval-shaped one in the pictures, above). It's good, but I still prefer the Snark.
There's no excuse not to be in perfect pitch with these instruments so easily available. Tuning with one of these little wonder devices is a snap. All digital, they are so accurate it's scary. The only drawback: they're battery powered and seldom (if ever) accept rechargeable batteries (and the batteries are often inconveniently located). But they're so inexpensive you can carry one in each of your cases.
A uke-specific tuner should have settings for C (GCEA) and D (ADF#B) tuning, but probably won't have a baritone setting (DGBE). Ideally, a uke-specific tuner would have settings for re-entrant and regular stringing, baritone and soprano/tenor scales.
General chromatic tuners can be used for any instrument - but try to avoid those designed solely for specific instruments like guitar, violin or banjo, since they have a limited range of tones and often won't work with ukes (unless they also have a chromatic tuner). Some chromatic tuners also have separate instrument settings.
Some ukes come with a plastic pitch-pipe tuner (see picture, left). More power to you if you can use it to stay in tune, but my advice is to dump it and buy a digital one. These aren't very accurate. Metal pitch-pipe tuners are generally much better, but more expensive than plastic, and still not as good as a digital one.
Geared versus friction tuners
Another source of hot debate is whether to use traditional friction tuners or more modern geared tuners. Tuners are also called machine heads. Traditionalists demand friction tuners. They call the visible tuning pegs on geared instruments "ears" and decry their appearance.
Nylon strings, especially new ones, stretch - even the ones sold as 'pre-stretched'. That means they go out of tune a lot until they're 'broken in'. Expect to tune your uke several times each time you play it, for several days, until the strings settle. During this time, you will really appreciate geared tuners. (A good chromatic tuner won't prevent having to retune a lot, but will help you keep the strings in precise tune while you're breaking them in.)
While it's a matter of personal taste as to which looks better, most friction tuners are neither as efficient nor as effective as geared tuners. Friction tuners are prone to slip more, and they take more time and effort to wrap strings when replacing them. Tuning with fiction tuners is often frustrating because even a very small adjustment can be too much, since the ratio is a simple one-to-one.
On almost all of my ukuleles with friction tuners, I have had to adjust the tuning more often than with geared tuners. That can be daily, weekly or between every song. The one exception is the Fluke, which remains in tune with very little adjustment required. I am not personally moved by their appearance, but I came from guitars where friction tuners are a rarity. On ukes, they strike me as an affectation and generally inefficient.
Friction tuners have a tiny screw on the head can be tightened to hold better. However, it's easy to over-tighten, and make it too hard to turn them. And, you may learn to your dismay, the thread can be stripped and you end up having to replace the entire peg! Sometimes it can crack the peg head, too, so be careful.
Friction tuners work best on soprano ukes where the tension is lowest of all sizes (see tensions, below). The few concert and tenor ukes I've had with friction heads (see my Republic and Waverly Street reviews) have had problems retaining string tension for even a single day.
Give me geared tuners any day. They stay in tune, take less time to wrap a new string (especially when you use a string winder), and are much, much more precise when tuning in small increments (they are 12-to-1 to 18-to-1 ratio, so you can make very small adjustments easily).
I prefer sealed tuners because they are easier to maintain, and less susceptible to building up dust and grime. But they also weigh a little more, which can be noticeable on a light ukulele. Open tuners give you easier access to the tightening screw if it proves necessary to adjust it (if geared tuners slip, tighten this screw a little), but require more frequent cleaning.
A hybrid type is the planetary tuner. This is really a geared tuner concealed within a friction tuner body. While considerably more efficient than a friction tuner (and even more accurate than most geared tuners), it is also more expensive and heavier. Because of its size, a planetary tuner cannot be directly fitted to an existing head to replace friction tuners without re-drilling the holes to accommodate the width. Planetary tuners are common on bluegrass banjos.
For some custom planetary tuners designed for ukuleles, check out pegheds.com.
Nylon-string ukuleles put less pressure on the bridge and top than guitars, even nylon stringed guitars. Larger ukes have more tension. According to Kawika, Inc. these are the approximate tensions on the various sizes ukes:
In comparison, a classical guitar has 75-90 lbs. of tension and a steel-string guitar has 150-200 lbs. tension. A concert would likely be around 35-36 lbs. Baritones tuned to GCEA will have much higher tension than with a DGBE tuning.
I have no figures on stress for steel string ukes, guitaleles or the U-bass. If anyone has the data, please email them to me.
WARNING: If you put steel strings on a ukulele, you're likely to pull the bridge right off because it's not designed for the extra tension. At the very least, you will warp the top and probably the neck.