How to reference or calculate the percentage pitch change between two notes?

Question

I'm building an arpeggiator software. So to start off I have a note for a piano sample, call it 'piano-base-note.mp3'. and I have a script to increase / decrease the pitch of an mp3 file by some percent. When the arpeggiator starts up, it will create the altered mp3 files needed to play the arpeggio. That is, it will change the pitch and save new copies. Right now I'm defining a 'note' in terms of percentage difference from the base note. I.e. to go down 50% in pitch would be `0.5`. To double pitch is `2.0`. Now I'm trying to use this percentage-based approach to make actual scales, and I'm not sure how. Is there some kind of chart to show the percent pitch change between two notes? Or a formula to calculate it?

Answer 1

Hi, does these “cents” diagrams help?

http://hyperphysics.phy-astr.gsu.edu/hbase/Music/cents.html

Each half-step is divided enter 100 cents.