Skip to content


Repository files navigation


npm version

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");


Generally, you just need to install tonal package (before it was called @tonaljs/tonal).

The API documentation is inside of each module 👇

Notes and intervals

Scales and chords


Keys, chord progressions

Time, rhythm



Read contributing document. To contribute open a PR and ensure:

  • If is a music theory change (like the name of a scale) link to reliable references.
  • If is a new feature, add documentation: changes to README of the affected module(s) are expected.
  • Ad tests: changes to the test.ts file of the affected module(s) are expected.
  • All tests are green


This library takes inspiration from other music theory libraries:

Projects using tonal

Showcase of projects that are using Tonal:

Thank you all!

Add your project here by editing this file


MIT License