How To Tune Acoustic Guitars

Learning how to tune an acoustic guitar correctly and efficiently is a necessary skill for any performing or recording guitarist. It can be crucial to group performance, listeners' enjoyment, and it is even more important for a recording. There are several methods for tuning the guitar, and I will go through each one to explain its  advantages.

First, you'll need:

• an acoustic guitar
• a guitar tuner or a keyboard or piano

Steps

1. String names. In standard tuning, the guitar strings are (from thickest to thinnest) E-A-D-G-B-E. If you choose to tune by piano, it is helpful to know where these notes are on that instrument as well. 
2. Tuning by piano. Pluck the low E string. To find it on the piano, locate middle C and move to the C two octaves below. Now move two white keys to the right.  That is the piano/keyboard E corresponding with the guitar's lowest string. Move to the right four white keys and you have A that corresponds with the guitar's A string. Move to the right four more keys and you will have the D that corresponds to the guitar's D string. Move to the right four more white keys and you will find the G that corresponds to the guitar's G string. Now, move three (note the difference here) more white keys to the right and locate the B that corresponds to the guitar's B string.  If you want to cheek to make sure you are doing it right, you should now be one white key to the left of middle C. For the last string, E, move from B four more white keys to the right. This is the E that corresponds to the guitar's thinnest string. 
3. Tuning with a guitar tuner. Tuning with a guitar tuner can be more effective that tuning with a piano if there is noise interfering with the details of the sound.  When a guitar is in tune with a tuner, the needle on the tuner's meter should be in the center. The tuner might sway back and forth, but gauge the guitar's pitch by where the tuner's needle eventually settles. Initial plucking of a string can produce all sorts of harmonics (higher pitches than the note you intend to play) which can disrupt the tuning process. 
4. Tuning the guitar to itself. There are two ways to tune the guitar to itself, but you should only do this if you know that one of your strings is in tune. The first way involves tuning the fifth fret of the guitar's low E string to its neighbor, the open A string. These notes are the same, only played on different strings. Do the same on the 5th fret of the A string with the open D string. Repeat this process for the next string, and after that use the 4th fret on the G string to tune to the open B string. Then repeat the original process with the high E string. The more you tune this way, the more you will grow accustomed to gauging tuning by the vibration of the strings. When a string is close but out of tune with another, there is a pulse or beating produced by the interaction of the two resonating frequencies. When they are perfectly in tune, the vibrating pulse disappears. 
5. Another way to tune the guitar to itself is to pick a note on a string that you know is in tune and tune the other strings to it.