81/55

Interval information

Ratio	81/55
Factorization	34 × 5-1 × 11-1
Monzo	[0 4 -1 0 -1⟩
Size in cents	670.1883¢
Name	undecimal acute paraminor fifth
Color name	1ug5, lugu 5th
FJS name	[math]\displaystyle{ \text{P5}_{5,11} }[/math]
Special properties	reduced
Tenney height (log2 nd)	12.1212
Weil height (log2 max(n, d))	12.6797
Wilson height (sopfr(nd))	28
Harmonic entropy (Shannon, [math]\displaystyle{ \sqrt{nd} }[/math])	~4.32628 bits
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81/55, the undecimal acute paraminor fifth, is an 11-limit interval. It is 243/242 (7.1 ¢) sharp of 22/15, and is the interval between 10/9 and 18/11, as well as between 11/9 and 9/5. It is also 55/54 flat of the perfect fifth (3/2). Most conspicuously, it is 81/80 sharp of 16/11, which is what leads to its name.

See also

• 110/81 – its octave complement
• Gallery of just intervals