### Posts by Category: Reference-Charts

### Semitone Interval Calculator

#### Intervals between frequencies

Reference-Charts, Flute-Making-Tools Jun 17

An interval is the difference between two musical notes: the distance between two frequencies, often expressed in semitones (or cents). The below tool calculates the exact number of semitones between any two given frequencies, or, given a frequency and an interval, will calculate the note required to achieve that interval.
**Some facts:**
A semitone is equal to 100 cents.
The twelve-tone equal temperament scale divides an octave into 12 semitones (of 100 cents each).
A theoretical model of an *equidistant heptatonic* scale, where all the intervals of the seven-note scale were perfectly equal, would result in an interval of 1.714 semitones each.

### Frequencies & Wavelengths of Musical Notes

#### Reference Chart

Resources, Reference-Charts Mar 17 2015

Instrument builders and technicians often need to do calculations that require knowing the frequency and/or wavelength of certain notes. The following table shows the frequencies of all the notes of a standard piano, to a thousandth of a hertz. I generated this table using a script I wrote in PHP. I’ve also published the underlying PHP array as a Gist on GitHub, that is freely available for use in your own website or project. Get it here.

### PHP Array of Musical Frequencies

#### Musical Notes to Frequency Table

Resources, Reference-Charts Mar 16 2015

Recently, I came across the need to reference a chart of musical notes and their frequencies, for the purpose of calculating the wavelengths of certain notes, and realized there wasn’t a great tool out there to do this automatically. So, I created a multi-dimensional PHP array so that I could access this data, loop through it, and make whatever calculations I needed to. Below is the resulting Gist, and it is available to use freely in your own projects. I used this PHP array to generate a handy reference table of musical frequencies and wavelengths, available here. More info about the topic of Musical Frequencies at this Wikipedia entry.