Ukulele action height
Kala's support guide on lowering a ukulele's action works with 3.0 mm (0.118″, just under 1/8″) at the 12th fret, on the G as well as the A string. Kala gives one figure for its sizes, and since the 12th fret is always halfway along the scale, the saddle rule is the same on soprano, concert and tenor.
Ukulele action, Kala
Height at the 12th fret on the G and A strings, from Kala's support guide.
| Instrument | Low (mm) | High (mm) | Relief (mm) | Fret |
|---|---|---|---|---|
| Ukulele | 3.0 | 3.0 | – | 12 |
How to use it
- Tune to G C E A. At the 12th fret, read the gap under the G (4th string) and under the A (1st string) with a steel rule.
- Enter the scale: 13″ soprano, 15″ concert (filled in) or 17″ tenor, and both readings.
- Slacken the strings, remove the saddle and sand its bottom by the amount shown. Restring, tune and measure again.
Help and explanations
Many ukuleles have no truss rod and no adjustable bridge, so the saddle is the adjustment you can make at home. The calculator turns your reading into how much to take off it.
How much to take off
The saddle moves twice what you want at the 12th fret. A concert uke measuring 3.8 mm there needs 1.6 mm off the saddle to reach Kala's 3.0 mm. That's a lot on a small saddle, so take off half, restring and measure before going further.
Sand on flat paper laid on a flat surface and keep the bottom square so the saddle seats fully in the slot. Leave the top alone: the strings should break cleanly over its crown.
When the saddle isn't the answer
If the action is fine at the 12th fret but the first chords feel hard, the nut slots are too high; that's a nut job. If strings buzz after lowering, look for a high fret before adding a shim.
A uke whose action rises after a dry winter or a humid summer may have a lifting bridge or a bulging top. See a repairer before you sand: lowering the saddle won't fix a moving bridge.
Tips
- High action makes a uke play sharp up the neck; after sanding, test the 12th fret of each string with the intonation checker.
- Fluorocarbon and Nylgut sets of the same size pull differently; see the figures for each in the string tension calculator.
- Replacing the nut or saddle? Ukulele string spacing shows where each string goes.
Frequently asked questions
What is the right action for a ukulele?
Kala works with 3.0 mm (0.118″) at the 12th fret, measured from the top of the fret to the underside of the string.
How do I lower the action on a ukulele?
Sand the bottom of the saddle by twice the change you want at the 12th fret: 0.8 mm off the saddle lowers the action there by 0.4 mm.
Is the action the same on soprano, concert and tenor?
Kala gives one figure, 3.0 mm at the 12th fret, and the 12th fret sits halfway along every scale, so the 2-to-1 saddle rule holds on all three.
Does a ukulele have a truss rod?
Many don't, especially sopranos and concerts. Without one, neck relief can't be adjusted, and action is set at the saddle and the nut.
Why are the first frets on my ukulele hard to press?
The nut slots are probably too high. Lowering the saddle won't fix it; the slots have to be filed carefully, or the nut replaced.