Why Guitar Frets Crowd Together Near the Body
Look closely at the neck of a guitar and you will see thin metal bars set across it. These bars are called frets, and they are not spaced evenly. Near the tuning pegs the frets sit far apart. Closer to the body of the guitar they crowd together more and more.
The reason has to do with how a string makes its sound. A plucked string vibrates, and the length of the part that is free to move decides the pitch. A long string makes a low note, and a shorter string makes a higher one. When a player presses a string down against a fret, only the part between that fret and the bridge can vibrate, so the note rises.
Each fret shortens the string by the same fraction of what is left, not by the same amount. As the vibrating part gets shorter, every step has less string to cut away. That is why the bars must sit closer together as they climb the neck.
The pattern has a neat result. The twelfth fret sits exactly halfway along the string. Pressing there gives the same note as the open string, only higher, a distance that musicians call an octave. A builder who measures the spacing with great care gives the guitar notes that sound in tune all the way up the neck.