Harmony
Tonic
The tonic is the first degree of a scale and the centre of gravity of a key: the note and chord (I) that music returns to for rest, like C in C major.
What is the tonic in music?
The tonic is the first degree of the scale, the note that gives the key its name. In C major the tonic note is C and the tonic chord is C, written I. In A minor it is A and the chord Am, written i.
It is the point of rest: when a melody or a chord progression lands on the tonic, your ear hears home. Every other scale degree is defined by its distance from it: D is the second, G the fifth, and so on.
How do you find the tonic of a song?
Three clues work in the vast majority of songs:
- The last chord. A song almost always ends on the tonic.
- The chord that sounds like an ending. Stop on each chord in turn: the one where silence feels satisfying is the tonic.
- The chord after the dominant. G7 pulls to C, E7 pulls to Am: the resolution points to the tonic.
Watch out for relative keys: C Am F G and Am F C G use exactly the same chords. If the song settles on Am, the tonic is A, not C.
How to hear the tonic on guitar
Let the open A string (5th string) ring as a drone, then play the A minor pentatonic at the 5th fret over it. Every time you land on an A (5th fret of the low E, 7th fret of the D string, 5th fret of the high E), the phrase sounds finished.
Do the same in C major: play C (x32010), then Dm, G, and back to C. Then find every C on the neck: 8th fret on the 6th string, 3rd fret on the 5th, 10th fret on the 4th, 5th fret on the 3rd, 1st fret on the 2nd. Ending your solo phrases on one of them is the simplest way to make them sound resolved.
What is tonic function?
In functional harmony every chord plays one of three roles: tonic (rest), subdominant (moving away) and dominant (tension). The basic cycle is T-S-D-T: C F G C, or C Dm7 G7 C in jazz.
The I chord is not alone in this role: vi (Am) and iii (Em) share two notes with C and can stand in for it. That is why the deceptive cadence G7 to Am works: you expected C and got a darker chord from the same family. In the library of chord progressions by style, each progression shows its Roman numerals, so you can spot where the I comes back.
Key takeaways
- The tonic is degree I: it names the key and acts as home base.
- To find it, listen to the final chord and to the chord that follows the dominant.
- I, vi and iii share tonic function and can replace one another.
- Ending a solo phrase on the tonic makes it sound resolved.
Frequently asked questions
What is the difference between the tonic and the root?
The root is the base note of a chord (G for G7). The tonic is the base note of a key. When you play C in C major the two coincide; in G7 in C major the root is G but the tonic is still C.
Does a song always start on the tonic?
No. Many songs start on vi or IV, for example Am F C G in C major. The first chord is a weak clue; the final chord and the resolutions after the dominant are far more reliable.
What is the tonic of a minor key called?
It is still called the tonic and is written as a lowercase i: Am in A minor, Em in E minor. A minor and C major share the same notes but not the same tonic, so they do not have the same point of rest.
Related terms
Practise in the workshop
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