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tonal is a music theory library. Contains functions to manipulate tonal elements of music (note, intervals, chords, scales, modes, keys). It deals with abstractions (not actual music or sound).

tonal is implemented in Typescript and published as a collection of Javascript npm packages.

It uses a functional programing style: all functions are pure, there is no data mutation, and entities are represented by data structures instead of objects.


import { Chord, Interval, Note, Scale } from "tonal";

Note.midi("C4"); // => 60
Note.freq("a4"); // => 440
Note.accidentals("c#2"); // => '#'
Note.transpose("C4", "5P"); // => "G4"
Interval.semitones("5P"); // => 7
Interval.distance("C4", "G4"); // => "5P"

// Scales
Scale.get("C major").notes; // => ["C", "D", "E", "F", "G", "A", "B"];
[1, 3, 5, 7].map(Scale.degrees("C major")); // => ["C", "E", "G", "B"]

Chord.get("Cmaj7").name; // => "C major seventh"

// Chord inversions
const triad = Chord.degrees("Cm");
[1, 2, 3].map(triad); // => ["C", "Eb", "G"];
[2, 3, 1].map(triad); // => ["Eb", "G", "C"];
[3, 1, 2].map(triad); // => ["G", "C", "Eb"];


Install all packages at once:

npm install --save tonal

You can read CHANGELOG here.


Tonal is compatible with both ES5 and ES6 modules, and browser.

ES6 import:

import { Note, Scale } from "tonal";

ES5 require:

const { Note, Scale } = require("tonal");


You can use the browser version from jsdelivr CDN directly in your html:

<script src=""></script>

Or if you prefer, grab the minified browser ready version from the repository.

Bundle size

tonal includes all published modules.

Although the final bundle it is small, you can reduce bundle sizes even more by installing the modules individually, and importing only the functions you need.

Note that individual modules are prefixed with @tonaljs/. For example:

npm i @tonaljs/note
import { transpose } from "@tonaljs/note";
transpose("A4", "P5");