Songs that are in the key of ... how do I know what key my guitar is tuned to?

I’ve noticed that songs are written in the key of… X
How do I know what key my guitar is tuned to, and, can I change back and forth from one key to another?

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Your guitar is not tuned to a key. It can be played in any key, like a piano can. A guitar doesn’t cover as many octaves as a piano, but it can play every note over 4 octaves (on a 24 fret guitar.)

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Guitars are not tuned to a key. *

The normal tuning ‘standard’ tuning for a guitar is a general purpose tuning you can play any key in.

So a key is a collection of notes that work together, based on the root note, so the C major key ( or scale) would be C D E F G A B , these can be notes or chords doesnt matter.

So you could make a song in the key of C by using C E and F chords say

  • there are non standard guitar tunings that make certain key’s easier (for chords) and certain ones harder…)
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C, F, and G for the key of C Major. The 1, 4, and 5 chords

it dont matter. Doesnt have to always be 1-4-5-4 etc

newstrings to expand on this the notes in a key are given numbers ( usually called the nashville number system, though its hundreds of years older than that).

So 1 is the root note ( a C ) , 4 and 5 are F and G.

So someone could say ‘this is a 12 bar blues in C’ and there is convention that that would be the 1 , 4 and 5 played in 12 bars (C,C,C,C,F,F,C,C,G,F,C,G - but more likely 7th chords), everyone would know what chords and when so could play along or solo using appropriate blues scales etc.

Standard rule for a major key is 1 4 5 chords major, 2 3 6 minor, 7 diminished. E Major doesn’t work in the key of C. I just don’t think you should be using a non-standard chord as an example when explaining how a key works.


Thank you all for responding. The truth is… I’m still such a beginner that most of what you are saying is going over my head. Perhaps I will comprehend more as my playing skill develops.
Thanks again!


Hey @newstrings, if your guitar is tuned to “standard tuning” like almost all guitars, you can play almost any song without changing the tuning.

Alternate tunings are something you’d explore way later, if ever.

You do not to change tuning to play different songs. With the standard tuning, you can play songs in any key.


The most common way of tuning a guitar is E A D G B E, strings 6 to 1 respectively, thickest to thinnest.

There are other options, which you don’t need to be distracted by for now.

I assume you are following Justin’s lesson and are somewhere in Grade 1.

You will have learned the first few open chords. Now I forget exactly how much theory Justin explains when he teaches those first chords.

Let’s consider the E chord. Again simplifying a basic open chord is typically made up of three notes. In the case of E it would be the notes E G# B. And the fingering you learn to play E is based on each string, either open or fretted, sounding one of those three notes eg open E string, 2nd fret on A string which is the note B.

When a song is written in a particular, that key is based on a scale, and the chords that can be constructed from the notes in that scale. For example in the key of C the available chords are C Dm Em F G Am Bdim (Bdim not frequently used).

If you follow the Practical Music Theory course (first two grades free, thereafter one of the few subscription-based courses) then you can learn all about this. But for now it is not necessary.

For now follow the modules during which process you’ll learn the first set of chords E D A Em Dm Am C and G. With those chords you can learn to play many songs. The fact that the song may be in the key of A or G is neither here nor there for now.


To add to this …

It is tuned in its own particular way with each string as you go from thick to thin having a certain ‘musical gap’ (called an interval between them. The tuning determines the shapes needed to make chords. On a guitar you can make each and every chord that exists (so long as it does not have more than 6 notes of course) and therefore can play in each and every key.

That E chord must be Em if you are discussing the key of C.


The scale degrees that chords are built on are given numbers.
C major scale:
C, D, E, F, G, A, B
Scale degrees:
1, 2, 3, 4, 5, 6, 7
Chords in the key of C major:
C, Dm, Em, F, G, Am, Bdim
Nashville numbering of chords:
1, 2, 3, 4, 5, 6, 7
Roman numeral numbering of chords:
I, ii, iii, IV, V, vi, vii


In which case, concentrate on learning to play. Just know that your guitar is not in a fixed or given key at all. Chords that you play belong to keys and combinations of chords you play will put you in one key or another - knowledge you will acquire further down the line.


Hi Skip! Your query is intriguing, and I actually try to tune my guitar to the key I want to play xD

@DavidP and @Richard_close2u have provided great advices that you will need. Keep going and have fun!

I play alternative tunings and in fact for every songs I encounter, I may have to adjust my tuning like a silly guy. Really. :rofl: The tuning that inspires me would be DADGAD (Dsus4) =)

Well… to get there you need to understand the fundamental chords shape on standard tuning EADGBE (Em11, it is actually a beautiful chord), develop the technique and muscle memory you need etc. It is really about applying what we have learnt from standard tuning to any other kind of tunings we want, that brings us creativity and tons of fun.

Thank you for your question Skip!

Yes, as others have mentioned, you can play music with your guitar in any key. This is called equal temperament, i.e. intervals greater than a semitone are divided into equal steps (semitones). This is the same thing that Justin demonstrates with the note circle.

Before equal temperament was invented, European music relied on Pythagorean tuning and just intonation. However, in those tuning systems, it was a real phenomenon that some instruments were better suited to play in a given key or a few keys, and were unusable in other keys. It was due to the fact that in non-equal temperament systems, the same interval in two different keys may have slightly different ratios in frequency. This does not happen in equal temperament, that’s why you can play practically in any key with a guitar or a piano.

Then there are instruments like the diatonic harmonica or the sitar that can only play in certain keys or have to be tuned to a particular key.

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Wow… I never knew that and very informative. Thanks József!

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What a great thread! New dude asks a simple, but very good question and the knowledge pours forth!

This definitely shows that music and how guitars produce it is not always that simple.

I hope @newstrings isn’t overwhelmed. Right now, the simple answer is that the song is written in a key, not the guitar. As you get through the first part of the course, and hopefully at some point add some music theory, it will become more clear.

Don’t fret too much about these things, they come with time and to the degree you need or want to, you can dive deep or not too deep.

One pitfall learning guitar is that guitar and music can be as complex as you want it to and if you look to deep and worry about the need to learn this vast subject, it could be discouraging.

You can play and enjoy to a significant degree without too much depth in the theory area, although some is definitely helpful. Let it come as it will.


Well, I’m not sure about Newstrings but I sure am overwhelmed however, being a complete newbie, I’ll happily stick to my module 6 of Lesson 1.
What a labyrinth of knowledge to be learnt.

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Yes. To add, equal temperament does not mean all notes in all keys are correct.

The best would be to play an instrument with just tuning, tuned to the key of the song.

Equal temperament means the tuning is ever-so-slightly wrong in all keys, but it is considered a good compromise as it allows the instrument to play all of them.

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Cannot mention that and not include this video where Jacob Collier demonstrates it by playing a piano tuned to equal temperament and showing what just tuning would be by his voice: