Sometimes, no matter how hard you try, your guitar just won’t stay in tune. This can be very frustrating, and it can seem like there is nothing you can do to correct your precious Gibson Les Paul Guitar.

“Intonation” on a guitar is basically fine-tuning, and if it isn’t right, your instrument might never sound in tune. Learning to check your intonation and correct it if necessary is a vital guitar setup technique, and it’s easy to do.

Pluck the open E string and lightly touch it over the 12th fret marker to play a harmonic. The 12th fret is usually marked with two dots instead of just one, and you should touch the string over the metallic strip which separates the 12th fret from the 13th. Pay close attention to the tone that sounds out. If you have an electric guitar tuner, you can measure the frequency with more accuracy.

Press the E string down at the 12th fret and play the note. If the fretted note is higher than the harmonic, the bridge needs to be moved slightly further away from the neck. If it is lower, then the bridge needs to be moved closer to the neck.

Find the adjustment screws for your saddles. The six saddles are found at the bridge of the guitar, and each has a groove for the six strings. If you have a Fender (or Fender-style) guitar, the screws will be found on the underside of the bridge, on the opposite side to the pickups. On Gibson guitarbridges (which have two separate pieces, a stop bar and a bridge) the screws are found on the pickups’ side of the saddles.

Turn the screw clockwise to move the saddles closer to it. This means that on a Fender-style bridge, turning the screw clockwise will move the saddle further away from the pickups. On a Gibson-style bridge, a clockwise turn will move the saddle closer to the pickups. Make a small adjustment and test the intonation again.

Repeat the process for the remainder of the strings. You might need to perform several small adjustments to get each string right. Once you’ve been through all six strings, you will have a perfectly fine-tuned, gig ready guitar.