The quickest and most accurate way to tune your guitar is to employ an electronic tuner. You need to know how to tune a guitar using an electronic tuner or some other fixed source if you want to play with other instruments or voices. This is the only way to ensure that everyone is playing by the same tuning rules. Besides, your guitar and strings are built for optimal tone production if you tune to standard pitch.
The electronic tuner is a handy device that seems to possess magical powers. Newer electronic tuners made especially for guitars can sense what string you’re playing, tell you what pitch you’re nearest, and indicate whether you’re flat (too low) or sharp (too high). About the only thing these devices don’t do is turn the tuning keys for you (although we hear they’re working on that).
In both types of tuners — the ones where you select the strings and the ones that automatically sense the string — the display indicates two things: what note you’re closest to (E, A, D, G, B, E) and whether you’re flat or sharp of that note.
To use an electronic tuner, you can either plug your guitar into the tuner (if you’re using electric) or use the tuner’s built-in microphone (to tune an acoustic). For most models, you simply turn the tuner on and play a note. The display will show you how close you are to the desired string and which direction to go. Bear in mind, some older, graph-type tuners require you to select which string you want to tune before you play the note.
Many electronic tuners are inexpensive (as low as $20 or so) and are well worth the money. Electronic tuners are usually powered by a 9-volt battery or two AAs, so they can go with you anywhere.