If the setting is too high, the nut bone needs to be removed and filed down from the underside.If it is too low, a sliver of cardboard or similar material may be inserted underneath, but this should be a temporary solution until a new bone of the right height can be obtained. On a classical guitar the height of the strings at the first fret will be about 1/16 in (1.5 mm).

At the bridge end, a similar adjustment can be made to the bridge bone to produce a height at the twelfth fret of approximately 3/16 in (5 mm). The reason the measurements are approximate is that the exact amount depends on the height of the frets and the total string length, both of which vary from maker to maker.

Note that these measurements are for the nylon string guitar. The metal strings of the acoustic guitar are set lower due to the greater tension, and for the sake of the left hand, steel strings need to be as low as is practical, consistent with clear sound.