12edo

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← 11edo 12edo 13edo →
Prime factorization 22 × 3 (highly composite)
Step size 100 ¢ (by definition) 
Fifth 7\12 (700 ¢)
(convergent)
Semitones (A1:m2) 1:1 (100 ¢ : 100 ¢)
Consistency limit 9
Distinct consistency limit 5
English Wikipedia has an article on:

12 equal divisions of the octave (abbreviated 12edo or 12ed2), also called 12-tone equal temperament (12tet) or 12 equal temperament (12et) when viewed under a regular temperament perspective, is the tuning system that divides the octave into 12 equal parts of exactly 100 ¢ each. Each step represents a frequency ratio of 21/12, or the 12th root of 2. It is the predominating tuning system in the world today.

Theory

12edo achieved its position as the standard Western tuning system through a combination of theoretical properties and practicality. It is the smallest number of equal divisions of the octave (edo) which can seriously claim to represent 5-limit harmony, and it represents a meantone temperament.

It divides the octave into twelve equal parts, each of exactly 100 cents. It has a fifth which is quite accurate at 700 cents, two cents flat of just. It has a major third which is 13.7 cents sharp of just, which, while reasonable for its size, is unsatisfactory for some. The minor third is even less accurate, being 15.6 cents flat of just.

Before people used 12edo, people used a variety of historical temperaments such as quarter-comma meantone, and later well temperaments. By the 20th century, 12edo became dominant primarily due to practical considerations for keyboard instruments and its ability to handle modulation across all keys with reasonable intonation. In actual performance, these deviations from just intonation are often reduced by the tuning adaptations of skilled performers. Modern music theory has increasingly treated 12edo as a system in its own right rather than as an approximation of just intonation or meantone, leading to theoretical approaches such as serialism and much of jazz harmony that derive from 12edo's structure as an equal division rather than its underlying temperament properties.[citation needed]

12edo is the basic example of a dodecatonic scale and can be considered the simplest well temperament, where all twelve fifths are the same.

The 7th harmonic (7/4) is represented by the diatonic minor seventh, which is sharp by 31 cents, and as such 12edo tempers out 64/63. The deviation explains why minor sevenths tend to stand out distinctly from the rest of the chord in a tetrad. Such tetrads are often used as dominant seventh chords in functional harmony, for which the 5-limit JI version would be 1–5/4–3/2–16/9, and while 12et officially supports septimal meantone for tempering out 126/125 and 225/224 via its patent val of 12 19 28 34], its approximations of 7-limit intervals are not very accurate. It cannot be said to represent 11 or 13 at all, though it does a quite credible 17 and an even better 19. Nevertheless, its relative tuning accuracy is quite high, and 12edo is the fourth zeta integral edo.

Stacking the fifth twelve times returns the pitch to the starting point, so that the Pythagorean comma, 312/219, is tempered out. Three major thirds equal an octave, so the lesser diesis, 128/125, is tempered out. Four minor thirds also equal an octave, so the greater diesis, 648/625, is tempered out. These features have been widely utilized in contemporary music. Other commas 12et tempers out include the diaschisma, 2048/2025, the septimal quartertone, 36/35, and the jubilisma, 50/49. Each affects the structure of 12et in specific ways, and tuning systems which share the comma in question will be similar to 12et in precisely those ways.

12edo also offers very good approximations to intervals in the 2.3.17.19 subgroup. This indicates one way to use 12edo that deviates from common-practice harmony; for instance the cluster chord 8:17:36:76 is well represented.

Prime harmonics

Approximation of prime harmonics in 12edo
Harmonic 2 3 5 7 11 13 17 19 23 29 31
Error Absolute (¢) +0.00 -1.96 +13.69 +31.17 +48.68 -40.53 -4.96 +2.49 -28.27 -29.58 -45.04
Relative (%) +0.0 -2.0 +13.7 +31.2 +48.7 -40.5 -5.0 +2.5 -28.3 -29.6 -45.0
Steps
(reduced)
12
(0)
19
(7)
28
(4)
34
(10)
42
(6)
44
(8)
49
(1)
51
(3)
54
(6)
58
(10)
59
(11)

Subsets and supersets

12edo contains 2edo, 3edo, 4edo, and 6edo as subsets. It is the 5th highly composite edo, 12 being both a superabundant and a highly composite number. 12edo is also the only known edo aside from 2edo that is both strict zeta and highly composite.

24edo, which doubles it, improves significantly on approximations to 11 and 13, with 13 tuned sharp. 36edo, which triples it, improves on harmonics 7 and 13, but has the 13 tuned flat instead of sharp. 72edo is a notable zeta-record edo, and 60-, 84-, and 96edo all see utilities. Notable rank-2 temperaments that augment 12edo with extra generators include compton and catler.

Intervals

Intervals of 12edo
Degree Cents Interval region Approximated 5-limit
JI intervals (error in ¢)
Audio Higher limit interpretations[note 1]
0 0 Unison (prime) 1/1 (just)
1 100 Minor second 256/243 (+9.775)
25/24 (+29.328)
16/15 (−11.731)
28/27 (+37.039), 21/20 (+15.533), 15/14 (−19.443)
17/16 (−4.955), 18/17 (+1.045)
19/18 (+6.397), 20/19 (+11.199)
2 200 Major second 9/8 (−3.910)
10/9 (+17.596)
8/7 (−31.174), 28/25 (+3.802)
17/15 (−16.687), 19/17 (+7.442),
55/49 (+0.020), 64/57 (−0.532)
3 300 Minor third 32/27 (+5.865)
6/5 (−15.641)
75/64 (+25.418)
7/6 (+33.129), 25/21 (−1.847)
19/16 (+2.487)
4 400 Major third 81/64 (−7.820)
5/4 (+13.686)
32/25 (-27.373)
63/50 (−0.108), 9/7 (−35.084)
34/27 (+0.910), 24/19 (−4.442)
5 500 Fourth 4/3 (+1.955)
27/20 (-19.551)
21/16 (-29.219)
6 600 Tritone 25/18 (+31.283)
36/25 (-31.283)
45/32 (+9.776)
64/45 (−9.776)
7/5 (+17.488), 10/7 (−17.488)
24/17 (+3.000), 17/12 (−3.000)
99/70 (−0.088), 140/99 (+0.088)
7 700 Fifth 3/2 (−1.955)
40/27 (+19.551)
32/21 (+29.219)
8 800 Minor sixth 128/81 (+7.820)
8/5 (−13.686)
25/16 (+27.373)
14/9 (+35.084), 100/63 (+0.108)
19/12 (+4.442), 27/17 (−0.910)
9 900 Major sixth 27/16 (−5.865)
5/3 (+15.641)
128/75 (-25.418)
12/7 (−33.129), 42/25 (+1.847)
32/19 (−2.487)
10 1000 Minor seventh 16/9 (+3.910)
9/5 (−17.596)
7/4 (+31.174), 25/14 (−3.802)
30/17 (+16.687), 34/19 (−7.442)
98/55 (-0.020), 57/32 (+0.532)
11 1100 Major seventh 243/128 (-9.775)
15/8 (+11.731)
48/25 (−29.328)
28/15 (+19.443), 40/21 (−15.533), 27/14 (−37.039)
32/17 (+4.955), 17/9 (−1.045)
36/19 (-6.397), 19/10 (-11.199)
12 1200 Octave 2/1 (just)
  1. Intervals of the 2.3.5.7.17.19 subgroup, with a few additional interpretations

Notation

The intervals and notes of 12edo have standard names from classical music theory. This classical notation system, which was in use before 12edo with other tuning systems based on chains of fifths, is sometimes called the chain-of-fifths notation or extended Pythagorean notation.

Semitones −2 −1 0 +1 +2
Symbol

The subsets 1edo, 2edo, 3edo, 4edo and 6edo can all be written using 12edo subset notation.

Any 12edo note or interval can be respelled enharmonically by adding a pythagorean comma to it or subtracting one from it.

Notation of 12edo
Degree Cents Standard notation
Diatonic (5L 2s) interval names Note names (on D)
0 0 Perfect unison (P1) D
1 100 Augmented unison (A1)
Minor second (m2)
D#
Eb
2 200 Major second (M2)
Diminished third (d3)
E
Fb
3 300 Augmented second (A2)
Minor third (m3)
E#
F
4 400 Major third (M3)
Diminished fourth (d4)
F#
Gb
5 500 Perfect fourth (P4) G
6 600 Augmented fourth (A4)
Diminished fifth (d5)
G#
Ab
7 700 Perfect fifth (P5) A
8 800 Augmented fifth (A5)
Minor sixth (m6)
A#
Bb
9 900 Major sixth (M6)
Diminished seventh (d7)
B
Cb
10 1000 Augmented sixth (A6)
Minor seventh (m7)
B#
C
11 1100 Major seventh (M7)
Diminished octave (d8)
C#
Db
12 1200 Perfect octave (P8) D

In 12edo:

  • Ups and downs notation is identical to standard notation;
  • Mixed sagittal notation is identical to standard notation, but pure sagittal notation exchanges sharps (♯) and flats (♭) for sagittal sharp () and sagittal flat () respectively.

Sagittal notation

This notation uses the same sagittal sequence as EDOs 5, 19, and 26, is a subset of the notations for EDOs 24, 36, 48, 60, 72, and 84, and is a superset of the notation for 6-EDO.

Evo flavor

12-EDO_Evo_Sagittal.svg

Because it includes no Sagittal symbols, this Evo Sagittal notation is also a conventional notation.

Revo flavor

12-EDO_Revo_Sagittal.svg

Solfege

Solfege of 12edo
Degree Cents Standard solfege
(movable do)
Uniform solfege
(2-3 vowels)
0 0 Do Da
1 100 Di (A1)
Ra (m2)
Du (A1)
Fra (m2)
2 200 Re Ra
3 300 Ri (A2)
Me (m3)
Ru (A2)
Na (m3)
4 400 Mi Ma (M3)
Fo (d4)
5 500 Fa Mu (A3)
Fa (P4)
6 600 Fi (A4)
Se (d5)
Pa (A4)
Sha (d5)
7 700 So Sa
8 800 Si (A5)
Le (m6)
Su (A5)
Fla (m6)
9 900 La La (M6)
Tho (d7)
10 1000 Li (A6)
Te (m7)
Lu (A6)
Tha (m7)
11 1100 Ti Ta (M7)
Do (d8)
12 1200 Do Da

Approximation to JI

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Selected 5-limit intervals approximated in 12edo

15-odd-limit interval mappings

The following tables show how 15-odd-limit intervals are represented in 12edo. Prime harmonics are in bold; inconsistent intervals are in italics.

Note that, since the cent was defined in terms of 12edo, the absolute and relative errors for 12edo are identical.

15-odd-limit intervals in 12edo (direct approximation, even if inconsistent)
Interval and complement Error (abs, ¢) Error (rel, %)
1/1, 2/1 0.000 0.0
3/2, 4/3 1.955 2.0
9/8, 16/9 3.910 3.9
13/11, 22/13 10.790 10.8
15/8, 16/15 11.731 11.7
5/4, 8/5 13.686 13.7
5/3, 6/5 15.641 15.6
7/5, 10/7 17.488 17.5
11/7, 14/11 17.508 17.5
9/5, 10/9 17.596 17.6
15/14, 28/15 19.443 19.4
13/7, 14/13 28.298 28.3
7/4, 8/7 31.174 31.2
7/6, 12/7 33.129 33.1
11/10, 20/11 34.996 35.0
9/7, 14/9 35.084 35.1
13/9, 18/13 36.618 36.6
15/11, 22/15 36.951 37.0
13/12, 24/13 38.573 38.6
13/8, 16/13 40.528 40.5
13/10, 20/13 45.786 45.8
11/9, 18/11 47.408 47.4
15/13, 26/15 47.741 47.7
11/8, 16/11 48.682 48.7
11/6, 12/11 49.363 49.4
15-odd-limit intervals in 12edo (patent val mapping)
Interval and complement Error (abs, ¢) Error (rel, %)
1/1, 2/1 0.000 0.0
3/2, 4/3 1.955 2.0
9/8, 16/9 3.910 3.9
15/8, 16/15 11.731 11.7
5/4, 8/5 13.686 13.7
5/3, 6/5 15.641 15.6
7/5, 10/7 17.488 17.5
11/7, 14/11 17.508 17.5
9/5, 10/9 17.596 17.6
15/14, 28/15 19.443 19.4
7/4, 8/7 31.174 31.2
7/6, 12/7 33.129 33.1
11/10, 20/11 34.996 35.0
9/7, 14/9 35.084 35.1
13/9, 18/13 36.618 36.6
15/11, 22/15 36.951 37.0
13/12, 24/13 38.573 38.6
13/8, 16/13 40.528 40.5
11/8, 16/11 48.682 48.7
11/6, 12/11 50.637 50.6
15/13, 26/15 52.259 52.3
11/9, 18/11 52.592 52.6
13/10, 20/13 54.214 54.2
13/7, 14/13 71.702 71.7
13/11, 22/13 89.210 89.2
15-odd-limit intervals by 12f val mapping
Interval and complement Error (abs, ¢) Error (rel, %)
1/1, 2/1 0.000 0.0
3/2, 4/3 1.955 2.0
9/8, 16/9 3.910 3.9
13/11, 22/13 10.790 10.8
15/8, 16/15 11.731 11.7
5/4, 8/5 13.686 13.7
5/3, 6/5 15.641 15.6
7/5, 10/7 17.488 17.5
11/7, 14/11 17.508 17.5
9/5, 10/9 17.596 17.6
15/14, 28/15 19.443 19.4
13/7, 14/13 28.298 28.3
7/4, 8/7 31.174 31.2
7/6, 12/7 33.129 33.1
11/10, 20/11 34.996 35.0
9/7, 14/9 35.084 35.1
15/11, 22/15 36.951 37.0
13/10, 20/13 45.786 45.8
15/13, 26/15 47.741 47.7
11/8, 16/11 48.682 48.7
11/6, 12/11 50.637 50.6
11/9, 18/11 52.592 52.6
13/8, 16/13 59.472 59.5
13/12, 24/13 61.427 61.4
13/9, 18/13 63.382 63.4

Regular temperament properties

Subgroup Comma list Mapping Optimal
8ve stretch (¢)
Tuning error
Absolute (¢) Relative (%)
2.3 [-19 12 [12 19]] +0.62 0.62 0.62
2.3.5 81/80, 128/125 [12 19 28]] −1.56 3.11 3.11
2.3.5.7 36/35, 50/49, 64/63 [12 19 28 34]] −3.95 4.92 4.94
2.3.5.7.17 36/35, 50/49, 51/49, 64/63 [12 19 28 34 49]] −2.92 4.86 4.87
2.3.5.7.17.19 36/35, 50/49, 51/49, 57/56, 64/63 [12 19 28 34 49 51]] −2.53 4.52 4.53
2.3.5.17 51/50, 81/80, 128/125 [12 19 28 49]] −0.87 2.95 2.95
2.3.5.17.19 51/50, 76/75, 81/80, 128/125 [12 19 28 49 51]] −0.81 2.64 2.64
  • 12et is monotonic to the 11-odd-limit. It is the first equal temperament to achieve this.
  • 12et has a lower relative error than any previous equal temperaments in the 3-, 5-, 7-, and 11-limit. The next equal temperaments doing better in those subgroups are 41, 19, 19, 22, respectively.
  • 12et is even more prominent in the 2.3.5.7.17.19 subgroup, and the next equal temperament that does this better is 72.

Uniform maps

13-limit uniform maps between 11.8 and 12.2
Min. size Max. size Wart notation Map
11.7554 11.8436 12cde 12 19 27 33 41 44]
11.8436 11.9329 12de 12 19 28 33 41 44]
11.9329 11.9962 12e 12 19 28 34 41 44]
11.9962 12.0256 12 12 19 28 34 42 44]
12.0256 12.2743 12f 12 19 28 34 42 45]

Commas

12edo tempers out the following commas. This assumes the val 12 19 28 34 42 44 49 51].

Prime
limit
Ratio[note 1] Monzo Cents Color name Name
3 (12 digits) [-19 12 23.46 Lalawama / Poma Pythagorean comma
5 648/625 [3 4 -4 62.57 Quadguma Diminished comma, greater diesis
5 (12 digits) [18 -4 -5 60.61 Saquinguma Passion comma
5 128/125 [7 0 -3 41.06 Triguma Augmented comma, lesser diesis
5 81/80 [-4 4 -1 21.51 Guma Syntonic comma, Didymus' comma, meantone comma
5 2048/2025 [11 -4 -2 19.55 Saguguma Diaschisma
5 (16 digits) [26 -12 -3 17.60 Sasa-triguma Misty comma
5 32805/32768 [-15 8 1 1.95 Layoma Schisma
5 (98 digits) [161 -84 -12 0.02 Sepbisa-quadtriguma Kirnberger's atom
7 256/245 [8 0 -1 -2 76.03 Ruruguma Bapbo comma
7 59049/57344 [-13 10 0 -1 50.72 Laruma Harrison's comma
7 36/35 [2 2 -1 -1 48.77 Ruguma Mint comma, septimal quarter tone
7 50/49 [1 0 2 -2 34.98 Biruyoma Jubilisma
7 3645/3584 [-9 6 1 -1 29.22 Laruyoma Schismean comma
7 64/63 [6 -2 0 -1 27.26 Ruma Septimal comma
7 3125/3087 [0 -2 5 -3 21.18 Triru-aquinyoma Gariboh comma
7 126/125 [1 2 -3 1 13.79 Zotriguma Starling comma
7 4000/3969 [5 -4 3 -2 13.47 Rurutriyoma Octagar comma
7 (12 digits) [-9 8 -4 2 8.04 Labizoguguma Varunisma
7 225/224 [-5 2 2 -1 7.71 Ruyoyoma Marvel comma
7 3136/3125 [6 0 -5 2 6.08 Zozoquinguma Hemimean comma
7 5120/5103 [10 -6 1 -1 5.76 Saruyoma Hemifamity comma
7 (16 digits) [25 -14 0 -1 3.80 Sasaruma Garischisma
7 (12 digits) [-11 2 7 -3 1.63 Latriru-asepyoma Metric comma
7 (12 digits) [-4 6 -6 3 0.33 Trizoguguma Landscape comma
11 128/121 [7 0 0 0 -2 97.36 Lulubima Axirabian limma
11 45/44 [-2 2 1 0 -1 38.91 Luyoma Undecimal fifth tone
11 56/55 [3 0 -1 1 -1 31.19 Luzoguma Undecimal tritonic comma
11 245/242 [-1 0 1 2 -2 21.33 Luluzozoyoma Frostma
11 99/98 [-1 2 0 -2 1 17.58 Loruruma Mothwellsma
11 100/99 [2 -2 2 0 -1 17.40 Luyoyoma Ptolemisma
11 176/175 [4 0 -2 -1 1 9.86 Loruguguma Valinorsma
11 896/891 [7 -4 0 1 -1 9.69 Saluzoma Pentacircle comma
11 441/440 [-3 2 -1 2 -1 3.93 Luzozoguma Werckisma
11 9801/9800 [-3 4 -2 -2 2 0.18 Biloruguma Kalisma
13 65/64 [-6 0 1 0 0 1 26.84 Thoyoma Wilsorma
13 91/90 [-1 -2 -1 1 0 1 19.13 Thozoguma Superleap comma, biome comma
13 144/143 [4 2 0 0 -1 -1 12.06 Thuluma Grossma
13 1001/1000 [-3 0 -3 1 1 1 1.73 Tholozotriguma Fairytale comma, sinbadma
13 4096/4095 [12 -2 -1 -1 0 -1 0.42 Sathuruguma Minisma
17 51/50 [-1 1 -2 0 0 0 1 34.28 Soguguma Large septendecimal sixth tone
17 52/51 [2 -1 0 0 0 1 -1 33.62 Suthoma Small septendecimal sixth tone
17 136/135 [3 -3 -1 0 0 0 1 12.78 Soguma Diatisma, fiventeen comma
17 256/255 [8 -1 -1 0 0 0 -1 6.78 Suguma Charisma, septendecimal kleisma
17 289/288 [-5 -2 0 0 0 0 2 6.00 Sosoma Semitonisma
17 2601/2600 [-3 2 -2 0 0 -1 2 0.67 Sosothuguguma Sextantonisma
19 39/38 [-1 1 0 0 0 1 0 -1 44.97 Nuthoma Undevicesimal two-ninth tone
19 96/95 [5 1 -1 0 0 0 0 -1 18.13 Nuguma 19th-partial chroma
19 153/152 [-3 2 0 0 0 0 1 -1 11.35 Nusoma Ganassisma
19 171/170 [-1 2 -1 0 0 0 -1 1 10.15 Nosuguma Malcolmisma
19 324/323 [2 4 0 0 0 0 -1 -1 5.35 Nusuma Photisma
19 361/360 [-3 -2 -1 0 0 0 0 2 4.80 Nonoguma Go comma
19 513/512 [9 3 0 0 0 0 0 -1 3.37 Lanoma Boethius' comma
  1. Ratios longer than 10 digits are presented by placeholders with informative hints.

Rank-2 temperaments

Periods
per 8ve
Generator* Pergen Temperaments
1 1\12 (P8, P4/5) Ripple, passion
1 5\12 (P8, P5) Meantone / dominant
2 5\12 (1\12) (P8/2, P5) Pajara, injera
3 5\12 (1\12) (P8/3, P5) Augmented / august
4 5\12 (1\12) (P8/4, P5) Diminished
6 5\12 (1\12) (P8/6, P5) Hexe

* Octave-reduced form, reduced to the first half-octave, and minimal form in parentheses if distinct

Rank-2 temperaments to which 12et can be detempered include compton (12 & 72), garibaldi (41 & 53), and diaschismic (46 & 58). For more comprehensive lists, see:

Octave stretch or compression

Whether there is intonational improvement from octave stretch and compression for 12edo varies by context. A slight compression such as what is given by 40ed10 and 34zpi shows improved intonation of harmonics 5 and 7 at the cost of worse 2 and 3; while stretching the octave for a purer 3 and for a better match of the inharmonicity on string instruments, like those in 7edf, 19edt, or 31ed6, also makes sense.

Scales

The two most common 12edo mos scales are meantone[5] and meantone[7].

  • Diatonic (meantone) 5L2s 2221221 (generator = 7\12)
  • Pentatonic (meantone) 2L3s 22323 (generator = 7\12)
  • Diminished 4L4s 12121212 (generator = 1\12, period = 3\12)

Non-mos scales

Due to 12edo's dominance, some non-mos scales are also widely used in many musical practices around the world.

  • Harmonic major – 2212132
  • Melodic major – 2212122
  • Hungarian minor – 2131131
  • Maqam hijaz / double harmonic major – 1312131
  • 5-odd-limit tonality diamond – 3112113

File:12edo modes.pdf

Well temperaments

For a list of historical well temperaments, see Well temperament.

Music

See also: Category:12edo tracks

The vast majority of music today is in 12edo or 12edo with slight modifications. As such, one can easily find 12edo music by going on any music streaming service.

See also

External links