Pitch ratios

Ascending Intervals Descending Intervals
Interval Frequency Ratio Interval Frequency Ratio
unison 1 : 1 unison 1 : 1
m2 1 : 1.059 minor 2nd 1 : 0.943
M2 1 : 1.122 Major 2nd 1 : 0.8909
m3 1 : 1.189 minor 3rd 1 : 0.84
M3 1 : 1.26 Major 3rd 1 : 0.7937
P4 1 : 1.334 Perfect 4th 1 : 0.749
aug4/dim5 1 : 1.4142 augm 4th/dim 5th 1 : 0.707
P5 1 : 1.498 Perfect 5th 1 : 0.667
m6 1 : 1.587 minor 6th 1 : 0.63
M6 1 : 1.682 Major 6th 1 : 0.595
m7 1 : 1.7818 minor 7th 1 : 0.561
M7 1 : 1.887 Major 7th 1 : 0.530
Octave 1 : 2 Octave 1 : 0.5

 

For ascending intervals greater than an octave, multiply the INTEGER portion
of the Frequency ratio by 2 for each successive octave (1, 2, 4, 8, etc.)

Examples:

– a minor tenth up = 2.189
– 2 octaves + a tritone up = 4.4142

For descending intervals greater than an octave, divide the Freq. ratio by
2 (if between 1 and 2 octaves), by 4 (if between 2 & 3 octaves), and so on.

Examples:

– an octave plus a perfect 4th down = 0.3745 ( 0.749/2 )
– 2 octaves plus a minor 3rd down = 0.21 ( 0.84/4 )

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