How High Should Your Guitar Strings Be?

A guitar can have fresh new strings, flawless frets and a perfectly straight neck, and still be a chore to play. More often than not, the reason comes down to a few tenths of a millimetre: the distance between the strings and the frets.

That distance is called string height, or action. Too high, and it tires the fretting hand, makes barre chords a struggle and pushes high notes slightly sharp. Too low, and the strings buzz and the sound chokes. In between lies a comfortable range, which varies with the instrument and the way you play. Here is how to measure it, which values to aim for, and above all in what order to work.

Action is measured from the underside of the string to the top of the fret, not down to the wood of the fingerboard. The most common convention is to take this measurement at the 12^th fret, halfway along the string, where the gap is meaningful and easy to read. Some manufacturers, Fender first among them, give their values at the 17^th fret: the figures are therefore not directly comparable, and it is always worth checking which fret a value refers to before using it.

Measure at least two strings: the highest (high E) and the lowest (low E on a guitar, E or low B on a bass). Bass strings vibrate with a wider amplitude and need a little more room, which is why values are always higher on the bass side.

On an electric guitar, going from 2.2 mm to 1.6 mm on the treble side sounds like nothing. Under the fingers, the difference is immediate: less pressure needed, smoother slides, chords that speak faster. Intonation benefits too, because a string pressed down from further away stretches more and goes slightly sharp.

The reverse is also true: action set too low for your attack will cause buzzing, especially when playing hard or bending strings. The right height is therefore not "as low as possible", but the lowest that stays clean with your way of playing. A light-touch player can go low; a heavy strumming hand, a thick pick or slide playing call for some margin.

The tools are modest: a steel rule marked in half-millimetres (ideally a string action gauge, graduated in fractions of a millimetre), a tuner and good light. A set of feeler gauges also comes in handy for small values.

1. Tune the instrument to your usual pitch and let it settle for a few minutes. Any measurement taken on slack strings is wrong.
2. Hold the guitar in playing position, or lay it flat on a support that holds the neck without stressing it.
3. Stand the rule on top of the 12^th fret, square to the strings, without pressing on the string being measured.
4. Read the mark level with the underside of the string, keeping your eye at the same height to avoid parallax error.
5. Note the treble-side and bass-side values. Keep these figures: they will be your reference point after each adjustment.

The ranges below are sensible starting points, cross-checked against specifications published by several manufacturers. They assume a properly adjusted neck and frets in good condition.

Measured at the 12^th fret, without a capo. For comparison, Fender specifies 1.6 mm (4/64") at the 17^th fret for its electric guitars with a 9.5" to 12" fingerboard radius.

The classical guitar is the exception: its low-tension nylon strings vibrate with a wide amplitude, and higher action is normal. Trying to give it the feel of an electric is the surest way to make it buzz all along the neck.

This is the most common mistake, and the most costly. A neck is never perfectly straight: it has a slight forward bow, called relief, which gives the strings room to vibrate. This bow is adjusted with the truss rod set inside the neck. It affects string height in the middle of the fingerboard, which is why many players are tempted to use it to lower their action.

The correct order never changes: first check and set the relief, then the string height at the bridge, then the height at the nut, the pickup height and finally the intonation. Each step depends on the one before. Setting the action on a neck with too much or too little relief is building on sand: everything will need redoing.

Two thumbwheels or two screws, one at each end, raise or lower the whole bridge. Set the treble and bass sides separately, in small quarter turns, retuning before each measurement. The saddle radius is fixed: the middle strings are not adjusted one by one.

On a Stratocaster, most hardtail bridges and basses, each string has its own saddle resting on two small grub screws. Turn both by the same amount to keep the saddle level. Set the two outer strings first, then the middle strings so that they follow the curve of the fingerboard. A radius gauge placed under the strings, near the bridge, makes this step much easier.

On an acoustic, nothing turns: the height depends on the saddle, the small strip of bone or synthetic material seated in the bridge. To lower the action, sand the underside of the saddle, keeping it perfectly flat. A simple rule of thumb: removing 1 mm from under the saddle lowers the height at the 12^th fret by about 0.5 mm. This cannot be undone, so it is best done on a spare saddle, keeping the original intact.

Some signs show that string height is only the symptom of a deeper problem:

• the saddles are already at their lowest and the action is still too high: the neck angle is probably the cause;
• the truss rod is seized, or reaches the end of its travel with no effect;
• a single area of the fingerboard buzzes whatever the height: one fret is probably higher than its neighbours;
• on an acoustic, the bridge is lifting, or the top bulges noticeably behind it.

In these cases, pushing on will only make things worse: no adjustment will lastingly correct a structural fault. A check-up first confirms what can be solved by a simple setup. If the problem lies in the instrument itself (neck angle, frets, bridge or top), it is a job for a luthier.