The unit: semitones
Western music divides the octave into 12 equal steps called semitones or half steps. Open Music Theory, an open textbook, measures intervals by counting the half steps between two pitches, and the twelve chromatic intervals add up to the octave. On a guitar one semitone is one fret: each fret represents one semitone, and the twelfth fret is the octave.
Here are all twelve pitches in order. After B the list starts again at C, one octave higher.
| Step | 0 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|
| Note | C | C♯ | D | E♭ | E | F |
| Step | 6 | 7 | 8 | 9 | 10 | 11 |
| Note | F♯ | G | A♭ | A | B♭ | B |
Sharp and flat names for the same pitch, such as C♯ and D♭, sound identical on a guitar. This page uses one common spelling for each.
How to transpose by hand
- Find the distance. Count semitones from the old key to the new one. G to A is 2 up; G to E is 3 down.
- Move each root. Shift the letter part of every chord by that many steps along the row above.
- Keep the rest. Minor, 7, sus4, add9 and the like stay exactly as they are.
- Move slash bass notes too. In D/F♯ both D and F♯ move by the same amount.
The same progression moved by different amounts:
| Move | G | Em | C | D7 |
|---|---|---|---|---|
| +2 | A | F♯m | D | E7 |
| +3 | B♭ | Gm | E♭ | F7 |
| −2 | F | Dm | B♭ | C7 |
| +5 | C | Am | F | G7 |
A singer usually asks for a change like this when a song sits too high or too low. Sing or play the first lines in the new key before rewriting the whole sheet.
Up or down: two ways to the same key
Twelve semitones make an octave, so moving up n semitones lands on the same chord names as moving down 12 − n. Up 5 and down 7 both turn G into C; the only difference is the octave, which for a singer is the whole point. The table pairs each move with its interval name and its counterpart in the other direction:
| Up | Interval | Same names as | G becomes |
|---|---|---|---|
| 1 | minor 2nd | down 11 | A♭ |
| 2 | major 2nd | down 10 | A |
| 3 | minor 3rd | down 9 | B♭ |
| 4 | major 3rd | down 8 | B |
| 5 | perfect 4th | down 7 | C |
| 6 | aug. 4th / dim. 5th | down 6 | C♯ |
| 7 | perfect 5th | down 5 | D |
| 8 | minor 6th | down 4 | E♭ |
| 9 | major 6th | down 3 | E |
| 10 | minor 7th | down 2 | F |
| 11 | major 7th | down 1 | F♯ |
| 12 | octave | no change | G |
When a song is too high, move it down, and pick the smaller of the two numbers if both would work. A move of 6 semitones, an augmented fourth or diminished fifth, is the same distance either way.
What a capo does
A capo clamps across all the strings at one fret and uses that fret as a new nut. Everything you play above it sounds higher by the number of frets covered. You keep the fingerings you know from open position, and the key changes. Because one fret is one semitone, the arithmetic is the same as transposing:
Song sheets for capo songs can name either the shapes you finger or the chords that sound, so check which one a sheet uses. The chart below translates five open major shapes.
| Capo | C shape | A shape | G shape | E shape | D shape |
|---|---|---|---|---|---|
| Fret 1 | C♯ | B♭ | A♭ | F | E♭ |
| Fret 2 | D | B | A | F♯ | E |
| Fret 3 | E♭ | C | B♭ | G | F |
| Fret 4 | E | C♯ | B | A♭ | F♯ |
| Fret 5 | F | D | C | A | G |
| Fret 6 | F♯ | E♭ | C♯ | B♭ | A♭ |
| Fret 7 | G | E | D | B | A |
Minor shapes work the same way: an Am shape with the capo at fret 3 sounds as Cm, an Em shape at fret 2 as F♯m.
Where to put the capo for a key
Work it backwards: the fret is the target key minus the key of the shapes you want to play, counted in semitones and wrapped around 12. The table gives the fret for four common sets of shapes. Pick the column with the lowest fret, since the strings get shorter and the frets narrower further up.
| To sound in | G shapes | C shapes | D shapes | E shapes |
|---|---|---|---|---|
| C | 5 | open | 10 | 8 |
| C♯ | 6 | 1 | 11 | 9 |
| D | 7 | 2 | open | 10 |
| E♭ | 8 | 3 | 1 | 11 |
| E | 9 | 4 | 2 | open |
| F | 10 | 5 | 3 | 1 |
| F♯ | 11 | 6 | 4 | 2 |
| G | open | 7 | 5 | 3 |
| A♭ | 1 | 8 | 6 | 4 |
| A | 2 | 9 | 7 | 5 |
| B♭ | 3 | 10 | 8 | 6 |
| B | 4 | 11 | 9 | 7 |
Example: a song in B♭ is awkward in open position. With G shapes the capo goes on fret 3, with E shapes on fret 6, so G shapes are the easier choice. Either way, every chord on the sheet moves by the same number of frets.
A worked song sheet
A song sheet is written in C, and the singer wants it 3 semitones lower, in A. Step one moves every chord down 3:
| Written | C | Am | F | G | Em | Dm |
|---|---|---|---|---|---|---|
| In A | A | F♯m | D | E | C♯m | Bm |
| G shapes | G | Em | C | D | Bm | Am |
The second row is correct but has F♯m, C♯m and Bm, three barre chords in their usual shapes. Step two puts the capo on fret 2, because A is 2 semitones above G, and moves every chord down 2 more to get the shapes to finger, the third row. With the capo on, those G-family shapes sound exactly as the second row. The singer hears A, the guitarist is down to one barre chord, Bm, and the arithmetic is the same two subtractions every time.
Practical tips
- Tune first, capo second. Tune the open strings with the online tuner, then add the capo and check each string again in chromatic mode.
- Write both names on your sheet, the shape and the sounding chord, if you play with others. The bass player needs the sounding chord.
- Keep the tempo. A key change moves pitch, not speed; practice the new shapes at the song's tempo with the metronome.
- For alternate tunings, the same arithmetic applies to the tuned strings; see the guitar tunings chart.
Frequently asked questions
How do I transpose chords to another key?
Count the semitones between the old key and the new one, then move every chord root by that many semitones and keep the rest of the chord name. From G to A is 2 semitones up, so G becomes A, Em becomes F♯m, C becomes D and D7 becomes E7.
What does a capo do to the key?
A capo clamps across the strings at one fret and acts as a new nut. Each fret is one semitone, so a capo at fret n raises every open string, and every chord shape you play, by n semitones. A G shape with the capo at fret 2 sounds as A.
Where do I put the capo to play in a key with easy chords?
Subtract the key of the shapes you want to use from the key you need, in semitones, and that is the fret. To sound in B♭ with G shapes: B♭ is 3 semitones above G, so capo at fret 3. If the answer is above about 7, use different shapes for a lower fret.
Do minor and seventh chords change differently?
No. The quality stays the same; only the root moves. Am moved up 3 semitones is Cm, G7 moved up 3 is B♭7. That is why transposing keeps the sound of a song and only changes its pitch.
Why does the chart write E♭ and not D♯?
They are the same pitch on a guitar, one fret apart from both D and E. Written music picks the spelling that fits the key, but for chord charts either name works. The chart uses the spellings most often seen in guitar chord sheets.
Sources
- Open Music Theory (Hybrid Pedagogy Publishing, CC BY-SA 4.0): Intervals and dyads (counting half-steps or semitones between pitches; the chromatic intervals add up to 12 in the octave; interval names by size)
- Wikipedia, Fret: on instruments such as guitars, each fret represents one semitone in the standard western system; the twelfth fret divides the string in half
- Wikipedia, Capo: clamps across the strings, uses a fret to create a new nut at a higher note, so players can change key with the same fingerings