Septimal major third
| Inverse | septimal minor sixth |
|---|---|
| Name | |
| Other names | Supermajor third |
| Abbreviation | S3, SM3 |
| Size | |
| Semitones | ~4½ |
| Interval class | ~4½ |
| Just interval | 9:7 |
| Cents | |
| Equal temperament | 400 |
| 24 equal temperament | 450 |
| Just intonation | 435 |
In music, the septimal major third 
play , also called the supermajor third (by Hermann Helmholtz among others) and sometimes Bohlen–Pierce third is the musical interval exactly or approximately equal to a just 9:7 ratio of frequencies, or alternately 14:11. It is equal to 435 cents, sharper than a just major third (5:4) by the septimal quarter tone (36:35) ( play ). In 24-TET the septimal major third is approximated by 9 quarter tones, or 450 cents ( play ). Both 24 and 19 equal temperament map the septimal major third and the septimal narrow fourth (21:16) to the same interval.
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