Press Play for A half sharp, 452.89 Hz, then pick any quarter tone from middle C up.
Quarter Tone Generator: 452.89 Hz sine tone
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Sine wave · both channels
Hz
Period 2.21 ms
Wavelength 75.7 cm (29.8 in)
50 cents above A4
Ready. It starts quiet and fades in over half a second.
A steady tone can harm ears and speakers before it sounds loud. Hear nothing? Do not turn it up to find the tone: small speakers cannot play very low tones, and many adults cannot hear very high ones.
Percent of this tool's loudest. Your device volume does the rest.
This quarter tone generator plays the pitches that lie halfway between piano keys, from middle C up to the next C. The list goes key, quarter tone, key, so each one can be heard against both neighbors.
Read the full guide
Hear a quarter tone against its neighbors
1. Press Play. A half sharp sounds: 50 cents above the 440 Hz A, a pitch no piano key has.
2. Press A, the 440 Hz tuning note, then A half sharp, between A and B flat, then B flat, a black key. The middle one sits evenly between the other two.
3. To learn a written quarter tone, find its row, leave it sounding and sing or play until your note matches it.
4. For a scale that uses them, press Maqam Rast on C, as written over the list, then its eight rows in order. The third and seventh notes are half flat.
Questions and answers
What is a quarter tone?
Half of a semitone: 50 cents. Dividing the octave into 24 equal steps instead of 12 gives the quarter-tone scale, or 24-tone equal temperament.
What frequency is a quarter tone above A 440?
452.89 Hz. Multiply any frequency by about 1.0293 to go up a quarter tone, or divide by it to go down: a quarter tone under 440 Hz is 427.47 Hz, the row A half flat.
How are quarter tones written?
Commonly with four extra signs. A half sharp raises a note by one quarter tone, a sharp and a half by three. A half flat and a flat and a half lower it as far. E half flat lies midway between E flat and E.
Which music uses quarter tones?
Many Arabic maqam scales are written with half flats, mostly on E and B, and many Persian dastgah hold three-quarter-tone steps. In practice the 24-step scale is a way of writing: players shade the notes by ear, so treat each row as the written pitch.
Can you hear a quarter tone?
Side by side, usually yes. About 5 to 6 cents has been given as the smallest pitch step people tell apart, and a quarter tone is 50. Press a key row, then the row after it. This is ear practice, not a hearing test.
All 25 notes
Quarter tones between the keys 12
C half sharp, between C and D flat269.29 Hz, 50 cents above middle C: one quarter tone. Also written D flat and a half.
D half flat, between D flat and D285.3 Hz. Three steps above middle C: a neutral second, or three-quarter tone. Also written C sharp and a half.
D half sharp, between D and E flat302.27 Hz. Five steps, 250 cents: wider than a whole tone, narrower than a minor third. Also written E flat and a half.
E half flat, between E flat and E320.24 Hz. Seven steps, 350 cents: the neutral third, between minor and major. The third note of maqam Rast on C.
E half sharp, between E and F339.29 Hz. Nine steps, 450 cents: between a major third and a perfect fourth. Also written F half flat.
F half sharp, between F and G flat359.46 Hz. Eleven steps, 550 cents: within 2 cents of the eleventh harmonic, 11 to 8. Also written G flat and a half.
G half flat, between G flat and G380.84 Hz. Thirteen steps, 650 cents: one quarter tone short of the perfect fifth. Also written F sharp and a half.
Show all 25 notes (18 more)
Quarter tones between the keys, continued
G half sharp, between G and A flat403.48 Hz. Fifteen steps, 750 cents: between the perfect fifth and the minor sixth. Also written A flat and a half.
A half flat, between A flat and A427.47 Hz. Seventeen steps, 850 cents: the neutral sixth. After E and B, the half flat most used in maqam scales.
A half sharp, between A and B flat452.89 Hz, the note this page opens on. Nineteen steps, 950 cents: between the major sixth and the minor seventh.
B half flat, between B flat and B479.82 Hz. Twenty-one steps, 1,050 cents: the neutral seventh, and the seventh note of maqam Rast on C.
B half sharp, between B and C508.36 Hz, 50 cents under the next C. Also written C half flat.
Piano keys, C to C 13
C, middle C on a piano261.63 Hz. The scale starts here: a row's steps and cents are counted up from this note.
D flat, a black key277.18 Hz, also written C sharp. Two steps above middle C: one semitone, 100 cents.
D, a white key293.66 Hz. Four steps above middle C: a whole tone, which gives the quarter tone its name.
E flat, a black key311.13 Hz, also written D sharp. Six steps, 300 cents: the minor third above middle C.
E, a white key329.63 Hz. Eight steps, 400 cents: the major third above middle C.
F, a white key349.23 Hz. Ten steps, 500 cents: the perfect fourth above middle C.
G flat, a black key369.99 Hz, also written F sharp. Twelve steps, 600 cents: exactly half the octave.
G, a white key392 Hz. Fourteen steps, 700 cents: the perfect fifth above middle C.
A flat, a black key415.3 Hz, also written G sharp. Sixteen steps, 800 cents: the minor sixth above middle C.
A, the 440 Hz tuning note440 Hz, the pitch standard. Every frequency here is 440 times 2 to the power of a number of steps over 24.
B flat, a black key466.16 Hz, also written A sharp. Twenty steps, 1,000 cents: the minor seventh above middle C.
B, a white key493.88 Hz. Twenty-two steps, 1,100 cents: the major seventh above middle C.
C, one octave above middle C523.25 Hz, twice middle C: 24 steps of 50 cents make the 1,200 cents of an octave.
How this list was compiled: Original list for this page; every tone is made in the visitor's browser by this page's own tone generator. Frequencies are computed, not looked up: 24 equal steps to the octave from A = 440 Hz, each step a factor of the 24th root of two, rounded to two decimal places. Cents are computed at 50 to a step. Checked on 2026-10-06 against Wikipedia: https://en.wikipedia.org/wiki/Quarter_tone (a quarter tone is half a semitone, 50 cents, a frequency ratio of about 1.0293; 24 equal steps to the octave; three steps give a neutral second or three-quarter tone; the table of interval sizes in 24 equal steps, with the neutral third at 350 cents, the neutral sixth at 850, the neutral seventh at 1,050 and 550 cents against the ratio 11 to 8 at 551.32 cents; maqam Rast written as C, D, E half flat, F, G, A, B half flat, C); https://en.wikipedia.org/wiki/Accidental_(music) (the signs half flat, flat and a half, half sharp and sharp and a half); https://en.wikipedia.org/wiki/Neutral_third (wider than a minor third, narrower than a major third); https://en.wikipedia.org/wiki/Rast_(maqam) (a half-flat third and a half-flat seventh); https://en.wikipedia.org/wiki/Arabic_maqam (the 24-step scale is a way of writing and does not fix how the notes are played; E, B and less often A are the half flats most used); https://en.wikipedia.org/wiki/Piano_key_frequencies (the keys from middle C, with A at 440 Hz); https://en.wikipedia.org/wiki/Cent_(music) (a semitone is 100 cents; one author puts the smallest pitch step people can tell apart at about 5 to 6 cents). Wikipedia's text is under CC BY-SA 4.0; the facts were checked there and the wording is this site's own. Licence: own work