There is a particular disappointment that every guitar player knows: you sit down, play a chord you have practised for weeks, and it sounds wrong. Not wrong because your fingers slipped, but wrong in a sour, slightly seasick way that no amount of good technique can fix. Nine times out of ten, the guitar is simply out of tune. Strings stretch, temperature changes, and a guitar that was perfectly in tune yesterday can drift overnight. Tuning is not a chore you do once when you buy the instrument. It is the first thing you do every time you pick it up, and learning to do it quickly and reliably is one of the most useful skills a player can build.
The Guitar Tuner gives you a reference for each string. Standard tuning, the tuning used for the overwhelming majority of guitar music, runs from the lowest, thickest string to the highest, thinnest string as E, A, D, G, B, E. Players often remember it with a phrase such as "Eddie Ate Dynamite, Good Bye Eddie." The two E strings share a name but sit two octaves apart, so the low E sounds deep and the high E sounds bright. When a tuner says a string is "sharp," it means the pitch is slightly too high and the string needs loosening. When it says "flat," the pitch is slightly too low and the string needs tightening. That pair of words causes more confusion than anything else in tuning, so it is worth fixing in your mind before you touch a tuning peg: sharp means too high, flat means too low.
Tuning string by string
Start with the low E string, the thickest one, and work your way across to the high E. There is a practical reason for this order. Changing the tension on one string changes the tension on the neck slightly, which nudges the other strings. Working in a consistent order, and then going back for a second pass, lets those small shifts settle. Tune each string until the tuner shows it is in tune, then move on, and when you have done all six, check them all again. The second pass almost always finds one or two strings that drifted while you tuned the others, especially on a guitar with fresh strings.
Turn the tuning pegs slowly. A quarter-turn is a large adjustment on most guitars, and beginners commonly overshoot, going from flat past in-tune to sharp and then back again. Small movements, followed by a pause to let the tuner settle, get you there faster than big twists. If a string is a long way out of tune, pluck it, adjust, pluck again, and repeat. Never force a peg that feels stuck; a stiff peg may need attention from someone who repairs guitars, and forcing it can snap a string or damage the mechanism.
Always tune up to the note rather than down to it, when you have the choice. If a string is sharp, loosen it until it is slightly flat, then tighten it back up to the correct pitch. Tuning up keeps the string under steady tension against the peg, which helps it stay in tune. Strings tuned down to pitch tend to slip flat again the moment you start playing, because the slack in the winding works itself out. This one habit, applied consistently, noticeably improves how long your guitar stays in tune during a practice session.
A worked example
Imagine you pick up your guitar after a week in its case. You pluck the low E string and the tuner shows it is flat by a clear margin. You tighten the peg slowly, plucking after each small turn, until the tuner shows E and holds steady. You move to the A string and find it is sharp, so you loosen it a little past the note, then tighten back up to A. The D string is close and needs only a tiny adjustment. The G string is flat, the B string is nearly right, and the high E string is flat by a small amount. You correct each in turn, then play an open E chord and listen.
On the second pass, the low E has slipped slightly flat again, because tightening the other strings changed the pull on the neck. You bring it back to E, recheck the A and D strings, and find them steady. Now you strum a few open chords: E, G, and C. They ring cleanly, with no wavering or beating sound between strings. The whole process took about two minutes. That is the normal shape of tuning: a first pass that fixes the big errors, a second pass that catches the drift, and a final listen to open chords as a reality check. If a chord still sounds sour after the tuner says every string is correct, check your finger placement before blaming the tuner; a finger pressing a string slightly sideways can bend it sharp.
Checking by ear
A tuner is a wonderful tool, but it is worth learning the old relative-tuning method as a backup, because tuners run out of battery and phones run out of charge. The method uses fretted notes: the fifth fret of the low E string should match the open A string, the fifth fret of the A string should match the open D string, the fifth fret of the D string should match the open G string, the fourth fret of the G string should match the open B string, and the fifth fret of the B string should match the open high E string. Play the fretted note and the open string together and listen for a wavering, pulsing sound. That pulsing, called beating, slows as the two notes get closer and disappears when they match. The G-to-B pair is the exception that trips everyone up: it is the fourth fret, not the fifth, because of the way standard tuning is laid out.
Ear tuning also teaches you something a tuner display cannot: what in-tune actually sounds like. Over time you will start to hear a slightly flat G string before you check it, and you will notice when a chord sounds wrong in the middle of a song. That listening skill transfers to everything else you play, from recognising when a bandmate is out of tune to hearing whether a recorded part is in tune with your own playing.
Common mistakes
The most common mistake is tuning in a noisy room and wondering why the tuner jumps around. Tuners listen to sound, and a television, a conversation, or another instrument in the room all compete with your guitar. Tune in a quiet moment, pluck one string at a time, and let each note ring. If you are using a tuner that listens through a microphone, hold the guitar close to it and damp the other strings with your palm so they do not ring sympathetically.
The second mistake is replacing strings one at a time in the wrong spirit, or rather, changing all six strings at once and then expecting the guitar to hold tune immediately. New strings stretch for a day or two. After fitting them, tune up, gently stretch each string by pulling it away from the fretboard a few times, retune, and repeat. It feels fiddly, but it shortens the stretching period from days to an evening, and it is far better than retuning every five minutes during practice.
The third mistake is ignoring the guitar itself. If one string keeps going out of tune while the others hold steady, the problem may be mechanical: a string binding in the nut slot, a slipping tuning peg, or an old string that has lost its elasticity. A guitar that will not stay in tune despite careful tuning is telling you something. A repairer can usually fix a binding nut or a worn peg cheaply, and fresh strings solve the rest.
When standard tuning is not the answer
Standard tuning covers most playing, but some songs use alternative tunings, such as dropping the low E string to D. If you are learning a song that sounds wrong in standard tuning even though your tuner says you are in tune, check whether the song uses a different tuning before assuming your ear is at fault. That said, beginners should stay in standard tuning until open chords feel comfortable. Alternative tunings are a creative choice, not a shortcut, and they make chord shapes you have learned behave differently.
Closing
Tuning is a small ritual that pays for itself every time you play. Tune in order, tune up to pitch, make a second pass, and finish by listening to open chords. The habit takes two minutes and transforms how your practice sounds. To explore the notes you can play once you are in tune, try the Guitar Chord Finder, and to build your sense of time alongside your sense of pitch, practise with the Online Metronome. For a related guide on a neighbouring instrument, read Bass Guitar Tuner Guide.