A diatonic harmonica is built in one key, yet players get three or more keys out of each harp. The trick is called a position: which note on the harp you treat as home. Once you know the three common positions, the question ‘which harmonica do I need for this song?’ becomes a lookup, and the table below answers it for all 12 keys.
01 Buy a C harp first
If you own one harmonica, make it a 10-hole diatonic in C. Almost every beginner book, video and tab assumes it, as do most of the songs in our free harmonica tab (a few are set for a D harp). When you add a second harp, an A harp is a common next buy because it plays blues in E, a favourite key for guitar-led jams. After that, add harps as the songs you actually play ask for them.
02 What a position is
On a C harp, 1st position (straight harp) uses C as home: the blow notes on holes 1, 4, 7 and 10. It suits folk tunes, hymns and campfire melodies in C major. 2nd position (cross harp) uses G as home: hole 2 draw and hole 3 blow. The draw notes on holes 1–4 outline a G chord and the bendable low draws sit right under your lips, which is why most blues, rock and country harmonica is played this way. 3rd position (slant harp) uses D as home: hole 1 and hole 4 draw. It gives a minor sound that suits minor blues and many modal folk tunes. The notes chart shows every hole, so you can see why each home note works.
03 Which harp for which song: the table
Find the song’s key in the left column, then read across to the harp you need for the style you want. For 3rd position, read the song key as a minor key: D minor on a C harp.
| Song key | 1st · straight (major tunes) | 2nd · cross (blues, rock) | 3rd · slant (minor) |
|---|---|---|---|
| C | C harp | F harp | B♭ harp |
| D♭ | D♭ harp | F♯ harp | B harp |
| D | D harp | G harp | C harp |
| E♭ | E♭ harp | A♭ harp | D♭ harp |
| E | E harp | A harp | D harp |
| F | F harp | B♭ harp | E♭ harp |
| F♯ | F♯ harp | B harp | E harp |
| G | G harp | C harp | F harp |
| A♭ | A♭ harp | D♭ harp | F♯ harp |
| A | A harp | D harp | G harp |
| B♭ | B♭ harp | E♭ harp | A♭ harp |
| B | B harp | E harp | A harp |
The pattern behind the table: for 2nd position, the harp is a fourth above the song (count up five half steps from the song key). For 3rd position, the harp is a whole step below the song. The 2nd-position pairs you will see quoted everywhere: G blues on a C harp, E blues on an A harp, A blues on a D harp.
04 How to find the key of a song
If you have the chords, the chord a song ends on is usually its key. If you only have a recording, hum the note the song feels like it wants to finish on, then find that note with a tuner or keyboard. For a 12-bar blues, the first chord is the key. Then use the table: a blues shuffle in E wants an A harp in 2nd position.
05 Which position should you learn first?
Start in 1st position, because simple melodies there need no bends; our beginner guide has a first two weeks that works. Move to 2nd position when you want blues, and learn it alongside bending, because the notes that make 2nd position sound bluesy are the bent draws on holes 2, 3 and 4. Leave 3rd position until 2nd feels comfortable.
Related reading
Questions
What key harmonica should a beginner buy?
A 10-hole diatonic in C. Most lessons and tab assume it, and it sits in a comfortable middle range.
What is cross harp?
Cross harp is 2nd position: playing a harp with its draw-chord note as home, so a C harp plays blues in G. It is the standard position for blues, rock and country.
What harmonica do I need for a song in E?
For blues or rock in E, use an A harp in 2nd position. For a major melody in E, use an E harp in 1st position. For E minor, use a D harp in 3rd position.
Do I need a different harmonica for every key?
Each harp covers several keys through positions, so you need fewer than you might think. A C, an A and a D harp cover blues in G, E and A.