HearmonyWhat Is a Semitone? Half Steps and Whole Steps Explained
A semitone, or half step, is the smallest interval in Western music: the distance from one piano key to the very next key, black or white, or from one guitar fret to the next. A whole step, also called a whole tone, is two semitones, like C to D. Every scale, interval and chord is built by counting these two steps.
What is a semitone?
A semitone is the distance between two neighboring keys on a piano, such as C to C♯ or E to F. Twelve semitones make up one octave, which is why the piano repeats its pattern of black and white keys every twelve keys.
In standard tuning (equal temperament), every semitone is the same size: the upper note's frequency is about 1.0595 times the lower one, the twelfth root of 2. Tuners measure it as 100 cents, so a note that is 50 cents off sits halfway to its neighbor.
The names vary by country and by context, but they mean the same thing:
| Size | American term | British term | Interval name | Example |
|---|---|---|---|---|
| 1 semitone | Half step | Semitone | Minor 2nd | E–F, B–C, C–D♭ |
| 2 semitones | Whole step | Tone (whole tone) | Major 2nd | C–D, E–F♯, B♭–C |
Where are the half steps on a piano?
Among the white keys there are exactly two half steps: E to F and B to C. Those are the only neighboring white keys with no black key between them. Every other pair of neighboring white keys is a whole step, with a black key in the middle.
| White keys | C–D | D–E | E–F | F–G | G–A | A–B | B–C |
|---|---|---|---|---|---|---|---|
| Step | Whole | Whole | Half | Whole | Whole | Whole | Half |
A half step doesn't always involve a black key, and a whole step doesn't always skip one: F♯ to G♯ is a whole step between two black keys. On guitar it's simpler still. One fret is a half step and two frets are a whole step, on every string.
How do half steps and whole steps build scales?
A scale is a fixed pattern of half and whole steps, and that pattern is what makes major sound major. The major scale is whole, whole, half, whole, whole, whole, half (W W H W W W H). Look at the white-key table above: starting on C, you get exactly that pattern, which is why C major uses only white keys.
Start the same pattern on G and you need one black key. G to A is whole, A to B whole, B to C half, C to D whole, D to E whole, but E to F is only a half step where the pattern needs a whole step, so F becomes F♯. G major is G A B C D E F♯ G. Our guide to the major scale builds it on all twelve notes.
- Natural minor: W H W W H W W. A B C D E F G A uses only white keys.
- Chromatic scale: nothing but half steps, all twelve notes in a row. See the chromatic scale for how to spell it going up and down.
- Whole-tone scale: nothing but whole steps, six notes per octave (C D E F♯ G♯ A♯), with a dreamy, floating sound.
How many semitones is each interval?
Every interval up to the octave is a count of semitones from 0 to 12. Count steps, not keys: from C to E you move C♯, D, D♯, E, which is four steps, even though five keys are involved.
| Semitones | Interval | From C |
|---|---|---|
| 0 | Unison | C–C |
| 1 | Minor 2nd (half step) | C–D♭ |
| 2 | Major 2nd (whole step) | C–D |
| 3 | Minor 3rd | C–E♭ |
| 4 | Major 3rd | C–E |
| 5 | Perfect 4th | C–F |
| 6 | Tritone (augmented 4th / diminished 5th) | C–F♯ / C–G♭ |
| 7 | Perfect 5th | C–G |
| 8 | Minor 6th | C–A♭ |
| 9 | Major 6th | C–A |
| 10 | Minor 7th | C–B♭ |
| 11 | Major 7th | C–B |
| 12 | Octave | C–C |
The semitone count tells you the size; the letter names tell you the interval's spelling. To learn what each one sounds like, the interval songs chart gives a well-known tune for every row.
How do you spell half steps and whole steps?
A whole step always uses neighboring letter names: E to F♯, not E to G♭, and B to C♯, not B to D♭. A half step can be spelled two ways, and the difference matters when you write scales.
- Diatonic half step: two different letters, such as C to D♭ or E to F. This is the minor 2nd you find inside scales.
- Chromatic half step: the same letter with an accidental, such as C to C♯ or B♭ to B. Strictly, that's an augmented unison, not a 2nd.
C♯ and D♭ are the same piano key (enharmonic notes), but the scale decides the name. Each letter appears once in a major scale, so F♯ major is F♯ G♯ A♯ B C♯ D♯ E♯: its seventh note is E♯, not F, even though you play the F key. In the same way, B♯ is the C key, F♭ is the E key and C♭ is the B key.
The accidentals follow the same sizes. A sharp (♯) raises a note by a half step, a flat (♭) lowers it by a half step, and a double sharp or double flat moves it a whole step.
How do you hear a half step vs a whole step?
A half step sounds tight and tense; a whole step sounds like an ordinary, relaxed step in a melody. Song openings make the two easy to recall:
| Step | Going up | Going down |
|---|---|---|
| Half step | "Jaws" theme (E→F) | "Für Elise" (E→D♯) |
| Whole step | "Frère Jacques" (C→D); "Happy Birthday," "-py" to "birth" (G→A, in C) | "Mary Had a Little Lamb" (E→D, in C) |
Played at the same time, a half step clashes hard, almost a buzz, while a whole step gives a milder rub. If you're unsure, sing up a major scale (do re mi fa sol la ti do) and notice the two places where the step feels pulled tight: mi to fa and ti to do. Those are the half steps.
Play C–D♭ and C–D five times each, then ask someone to play one of the two at random. Do ten random trials a day, and change the starting note each day, until you answer without hesitating.
Common mistakes
- Treating every white-key pair as a whole step. E–F and B–C are half steps. Forgetting this is the most common reason a scale comes out wrong.
- Counting the starting key. C to D is one whole step, not two keys' worth of steps. Count the moves, not the keys you touch.
- Spelling a whole step with the same letter. D to E is a whole step; D to D♯ is a half step, even though D♯ is closer to E than D is.
- Mixing up a minor 2nd and a minor 3rd by ear. Both can sound "dark" in a melody. The minor 3rd is a skip, as in "Greensleeves"; the half step is the smallest move there is.
Self-test: half step or whole step?
- E to F
- B♭ to C
- F♯ to G
- A to B
- C to D♭
- How many semitones are there from D up to A?
- Is E to G♭ a correctly spelled whole step?
Answers: 1. half. 2. whole. 3. half. 4. whole. 5. half. 6. Seven, a perfect fifth. 7. It's the right size but the wrong spelling; write E to F♯.
Practice half steps and whole steps in Hearmony
Hearmony, the iPhone ear-training app the Hearmony team builds, has a unit for exactly this. Interval Peaks opens with "Steps: seconds," which introduces the half step and the whole step side by side, going up and going down, then mixes them with the minor third so you learn to separate the smallest moves from small skips. Later units mix in every interval up to the octave.
Tuning Lab picks up where the half step ends. Its first lesson explains that a semitone is 100 cents, then asks whether a note is flat or sharp by smaller and smaller amounts, down to about 6 cents. The free Note Reading side quest shows where sharps sit on the keyboard. Get Hearmony on the App Store, and see ear training for beginners for the full order of skills.