The table shows the most widely used conventional names for the intervals between the notes of a chromatic scale. A perfect unison (also known as perfect prime)^[5] is an interval formed by two identical notes. Its size is zero cents. A semitone is any interval between two adjacent notes in a chromatic scale, a whole tone is an interval spanning two semitones (for example, a major second), and a tritone is an interval spanning three tones, or six semitones (for example, an augmented fourth).^[a] Rarely, the term ditone is also used to indicate an interval spanning two whole tones (for example, a major third), or more strictly as a synonym of major third.

Intervals with different names may span the same number of semitones, and may even have the same width. For instance, the interval from D to F♯ is a major third, while that from D to G♭ is a diminished fourth. However, they both span 4 semitones. If the instrument is tuned so that the 12 notes of the chromatic scale are equally spaced (as in equal temperament), these intervals also have the same width. Namely, all semitones have a width of 100 cents, and all intervals spanning 4 semitones are 400 cents wide.

The names listed here cannot be determined by counting semitones alone. The rules to determine them are explained below. Other names, determined with different naming conventions, are listed in a separate section. Intervals smaller than one semitone (commas or microtones) and larger than one octave (compound intervals) are introduced below.

Number of semitones	Minor, major, or perfect intervals	Short	Augmented or diminished intervals	Short	Widely used alternative names	Short	Audio
0	Perfect unison	P1	Diminished second	d2			Play (help·info)
1	Minor second	m2	Augmented unison[5][b]	A1	Semitone, half tone, half step	S	Play (help·info)
2	Major second	M2	Diminished third	d3	Tone, whole tone, whole step	T	Play (help·info)
3	Minor third	m3	Augmented second	A2			Play (help·info)
4	Major third	M3	Diminished fourth	d4			Play (help·info)
5	Perfect fourth	P4	Augmented third	A3			Play (help·info)
6			Diminished fifth	d5	Tritone	TT	Play (help·info)
			Augmented fourth	A4
7	Perfect fifth	P5	Diminished sixth	d6			Play (help·info)
8	Minor sixth	m6	Augmented fifth	A5			Play (help·info)
9	Major sixth	M6	Diminished seventh	d7			Play (help·info)
10	Minor seventh	m7	Augmented sixth	A6			Play (help·info)
11	Major seventh	M7	Diminished octave	d8			Play (help·info)
12	Perfect octave	P8	Augmented seventh	A7			Play (help·info)

Source: Interval (music) – Wikipedia