Guitar action is the height of the strings above the frets, measured at the 12th fret, and it determines how easy the guitar is to play. Low action is easier to play, because the strings are closer to the frets, but it can buzz, and high action is harder to play, but it rings more clearly, and the action is adjusted at the bridge and the nut.
What is guitar action?
Guitar action is the height of the strings above the frets, measured at the 12th fret, and it determines how easy the guitar is to play. Low action is easier to play, because the strings are closer to the frets, and less pressure is needed to hold them down, but it can buzz, because the strings have less room to vibrate, and they hit the frets. High action is harder to play, because the strings are further from the frets, and more pressure is needed, but it rings more clearly, because the strings have more room to vibrate, and they do not hit the frets. The action is typically about 2 millimetres on the treble side, and about 2.5 millimetres on the bass side, at the 12th fret, for an acoustic guitar, and a little lower for an electric guitar, because the electric strings are lighter, and they need less room. The action is adjusted at the bridge, by raising or lowering the saddle, and at the nut, by filing the nut slots, and at the truss rod, by adjusting the neck relief, which is the curve of the neck, and the three together set the action. The guitar tuner tunes the guitar, and the E major guitar chord is the chord the action is built on.
How guitar action works
Guitar action works because the strings vibrate when they are plucked, and the vibration needs room, or the strings will hit the frets, and buzz, and the action is the room, measured at the 12th fret, where the strings are highest above the frets. The action is set by the bridge, the nut, and the truss rod: the bridge sets the height at the body end, the nut sets the height at the headstock end, and the truss rod sets the curve of the neck, the relief, which is the slight bow, away from the strings, so the strings have room to vibrate in the middle of the neck. The action is a compromise, between playability and tone, and the player must choose: low action is easy to play, but it can buzz, and the tone is thinner, because the strings are closer to the frets, and high action is hard to play, but it rings clearly, and the tone is fuller, because the strings have more room to vibrate. A player who plays with a light touch can use low action, because the strings do not vibrate as much, and a player who plays hard needs higher action, because the strings vibrate more, and they need more room. The F major guitar chord is the chord most players first feel the action on, because it is a barre chord, and the action determines how hard it is to press.
Worked example — measuring the action. Measure the action at the 12th fret, with a ruler, from the top of the fret to the bottom of the string, and the treble side, the high E string, should be about 2 millimetres, and the bass side, the low E string, should be about 2.5 millimetres, for an acoustic guitar. If the action is higher, the guitar is hard to play, and the strings need more pressure, and the action should be lowered, by lowering the saddle at the bridge, or by adjusting the truss rod, to straighten the neck. If the action is lower, and the strings buzz, the action should be raised, by raising the saddle, or by loosening the truss rod, to give the neck more relief, so the strings have room to vibrate. The key of F major lists the chords the action affects.
How to practise checking guitar action
Practise checking your guitar action by measuring it at the 12th fret, and by listening for buzz, so you know whether the action is right, or whether it needs adjusting.
- Measure the action at the 12th fret, with a ruler, from the top of the fret to the bottom of the string, on the treble and bass sides, and write down the measurements.
- Play the I–V–vi–IV progression in C major and listen for buzz, especially on the barre chords, and note which strings buzz, and where.
- Play the F major barre chord, at the 1st fret, and listen for the strings to ring cleanly, and if they buzz, the action may be too low, or the technique may need work.
- Check the neck relief, by fretting the 1st and 14th frets, and looking at the gap at the 7th fret, which should be a small gap, about the thickness of a business card.
- Take the guitar to a luthier, or a guitar shop, for a setup, if the action is wrong, because the setup adjusts the bridge, the nut, and the truss rod, and it makes the guitar play its best.
Common mistakes
- Adjusting the truss rod without knowing how — The truss rod adjusts the neck relief, and turning it the wrong way, or too far, can damage the neck, because the truss rod is under tension, and the neck is wood, and the wood can crack. Leave the truss rod to a luthier, unless you know how to adjust it, and the guitar will be safe.
- Setting the action too low — Low action is easy to play, but it can buzz, because the strings have less room to vibrate, and they hit the frets, and the buzz will make the guitar sound bad, even if it is easy to play. Set the action low enough to be comfortable, but high enough not to buzz.
- Ignoring the action when the guitar is hard to play — A guitar that is hard to play may have high action, and the player will blame their technique, when the action is the problem, and the fix is a setup, not more practice. Check the action, and get a setup, if the guitar is hard to play, and the playing will be easier.
Quick reference
This table compares low and high action side by side, so you can see the trade-offs at a glance. Low action is easier to play, but it can buzz, and the tone is thinner, while high action is harder to play, but it rings clearly, and the tone is fuller, and the choice depends on the player and the style.
| Low action | High action | |
|---|---|---|
| Playability | Easy, less pressure needed | Hard, more pressure needed |
| Buzz | More likely, strings hit the frets | Less likely, strings have room |
| Tone | Thinner, less sustain | Fuller, more sustain |
| Best for | Light touch, fast playing | Hard strumming, slide guitar |
Use the table to decide your action: if you play with a light touch, and you want fast playing, use low action, and if you play hard, and you want a full tone, use high action, and get a setup, so the action is right for you. When the action is right, the guitar plays its best, and the playing is easy.
Frequently asked questions
What is guitar action?
Guitar action is the height of the strings above the frets, measured at the 12th fret, and it determines how easy the guitar is to play. Low action is easier, but it can buzz, and high action is harder, but it rings more clearly.
What is a good action for a guitar?
About 2 millimetres on the treble side, and about 2.5 millimetres on the bass side, at the 12th fret, for an acoustic guitar, and a little lower for an electric guitar, because the electric strings are lighter.
How is guitar action adjusted?
At the bridge, by raising or lowering the saddle, at the nut, by filing the nut slots, and at the truss rod, by adjusting the neck relief, which is the curve of the neck, and the three together set the action.
Can I adjust the action myself?
The saddle can be adjusted, by sanding it down, or by shimming it up, but the nut and the truss rod should be left to a luthier, unless you know how, because they can damage the guitar if they are done wrong.
Why does my guitar buzz?
Because the action is too low, and the strings hit the frets when they vibrate, or because the technique is wrong, and the fingers are not pressing the strings down firmly, or because the strings are old, and they vibrate unevenly. Check the action, the technique, and the strings, in order.