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Hi, I'm building ukuleles, mostly sopranos, and to date I've stuck with a scale length of 13.75 inches / 350mm, which was the size of the first soprano I built. That appears to be the most common scale length for them. But I'm wondering why those numbers. Every article I've read defines the scale of a soprano as 13 inches, but I've yet to find one that is exactly 13 inches. With smaller ukes it's even weirder, Ohana and their duplicators use a scale of 11 15/16th inches for sopraninos, which is a bit over 300mm. Why not just round it out at 12 inches? Is there something magic in the numbers that I'm missing? Some calculation process that gives these weird sizes? I'm in the process of building a uke with an overall length of just under 19 inches so it'll fit in an airline carry on bag without any issues. At the moment it looks like a scale of about 12 1/2 inches. I'm not even sure if that makes it a soprano or a sopranino?

Thanks

If you want a 13 inch scale soprano then look at the early Hawaiian ukulele manufacturers. My own Jonah Kumalae from (roughly) the 1920s has a 13 inch scale, as (I think) do all the others from the first ukes in the 1890s.

Ukulele production on the US mainland began after the 1914 Pan Pacific Exposition where Kumalae won a medal, proudly shown on their logo! The first Martin ukes were made soon after, but used a longer scale (I think 13 11/16 rather than 13 3/4), and they were extremely popular so the scale has been copied ever since. I don't think anyone knows wy they changed the scale, but my guess is that they used an existing guitar template (starting at the 9th or 10th fret) and picked the nearest scale which worked with that template.

Most of my sopranos are 13 inch scale because I like the playing feel a little better.

There is no magic calculation in any of these numbers, except that there is an optimum scale length for each gauge of string in a particular tuning. For your 12 1/2 inch scale uke, that is just a fraction short for standard uke strings in C tuning. It will work, but the strings might feel a touch flabby when playing and not intonate quite as well. Tuned up to D that scale will work well (and D was the original ukulele tuning for sopranos).

Thanks profchris,

I'm now thinking of building a Martin style uke, or one based on the vintage hawaiian instruments using a 13 inch scale. That'll put me on firmer ground and I'll see if I can't bring it in at 19 inches, even if that means the headstock looks a bit squat.

Smithy