Microtonal Scale Generator

This free microtonal scale generator lets you explore tunings beyond 12-tone equal temperament. Generate EDO scales from 5 to 53 divisions per octave, load non-Western presets like Maqam Rast, Slendro, Pelog, and Bohlen-Pierce, or build custom scales by editing cent values. Hear each note, compare every step to 12-TET, and export your scale as a Scala .scl file — all computed instantly in your browser.

EDO Divisions

12-EDO

Scale Preset

Root Note

Root Frequency (Hz)

Show 12-TET Comparison

Tempo 100 BPM

Ascend & Descend

12-EDO (Standard)

Divisions / Period

12 steps per octave

Step Size

100.000 cents

Period Ratio

2:1 (octave)

Root

A4 = 440.00 Hz

Scale Degrees

Step	Cents	Frequency (Hz)	Ratio	Nearest 12-TET	Deviation	Play

Custom Cent Editor

How to Use the Microtonal Scale Generator

Choose a Tuning System

Select an EDO division (5–53 equal steps per octave) using the slider, or pick a named preset like 19-TET, Maqam Rast, Slendro, or Bohlen-Pierce from the dropdown.

Set Root & Frequency

Choose a root note name and its exact frequency in Hz. The default is A4 = 440 Hz, but you can set any reference pitch for your tuning.

Explore & Listen

View every scale degree with its cent value, frequency, ratio, and nearest 12-TET note. Click Play on individual notes or play the full scale ascending and descending.

Edit & Export

Use the custom cent editor to add, remove, or tweak individual steps. Export your scale as a Scala .scl file for use in synthesizers and DAWs, or copy the table data.

Understanding Microtonal Tuning

What Is Microtonal Music?

Microtonal music uses intervals smaller than the semitone (100 cents) found in standard 12-tone equal temperament. Many world music traditions — Arabic maqam, Turkish makam, Indonesian gamelan, Indian raga — have always used microtonal intervals, including neutral thirds, neutral seconds, and various quarter-tone-adjacent pitches that sit between the keys of a standard piano. Western composers and experimentalists like Harry Partch, Ben Johnston, La Monte Young, and Wendy Carlos have also explored alternative tuning systems extensively. If you want to measure how far a pitch deviates from 12-TET in real time, try the microtone frequency calculator alongside this generator.

Equal Divisions of the Octave (EDO)

An N-EDO system divides the octave into N equal logarithmic steps, each of 1200 / N cents. Standard Western tuning is 12-EDO (100 cents per step). Popular alternatives include 19-EDO (better major thirds, close to 1/3-comma meantone), 22-EDO (used in Indian music theory and superpyth temperament), 24-EDO (the quarter-tone system used in Arabic and contemporary classical music, adding a 50-cent step between every 12-TET semitone), 31-EDO (excellent approximations of 5-limit just intervals, the basis of the historic Fokker organ), and 53-EDO (virtually indistinguishable from just intonation for Pythagorean and 5-limit intervals). Each EDO has a distinct harmonic character that becomes apparent when you compare it to pure just intonation ratios.

Non-Octave Tunings

Some tuning systems do not repeat at the octave (2:1 ratio). The Bohlen-Pierce scale divides the tritave (3:1) into 13 equal steps of approximately 146.3 cents each — it features its own consonances built around odd-number harmonics (3:5:7). Wendy Carlos Alpha (78¢ steps), Beta (63.8¢ steps), and Gamma (35.1¢ steps) are non-octave equal temperaments designed to approximate just intervals without the constraint of octave equivalence. These xenharmonic systems are genuinely incompatible with standard notation and require purpose-built software instruments.

The Scala .scl Format

The .scl (Scala scale) format is the standard interchange format for sharing tuning data with software synthesizers, samplers, and DAWs. A .scl file lists the number of scale degrees followed by their cent or ratio values, one per line. This tool generates valid .scl files you can load directly into compatible instruments such as Surge XT, ZynAddSubFX, Pianoteq, and any synth supporting MTS-ESP or the Scala application. The companion .kbm (keyboard mapping) file — not generated here — controls how those scale degrees are assigned to MIDI note numbers.

Frequently Asked Questions

What is EDO and how does it differ from standard tuning?

EDO stands for Equal Division of the Octave. Standard Western tuning is 12-EDO, dividing the octave into 12 equal steps of 100 cents each. Other EDO systems use different numbers of divisions — for example, 19-EDO has 19 steps of approximately 63.16 cents each, producing intervals that are impossible in 12-tone tuning.

Which EDO systems are most popular for microtonal music?

The most popular EDO systems include 19-EDO (better major thirds, used in Renaissance-inspired music), 24-EDO (quarter-tones, common in Arabic and contemporary classical music), 31-EDO (excellent just intonation approximations), and 53-EDO (nearly indistinguishable from just intonation for many intervals, historically studied in Turkish and Chinese music theory).

What are Maqam scales?

Maqam (plural: maqamat) is the system of melodic modes used in Arabic, Turkish, and Persian music. Each maqam defines a set of intervals, often including quarter-tones (approximately 50 cents) that do not exist in 12-TET. Maqam Rast and Maqam Bayati are two of the most fundamental maqamat, each with a distinctive emotional character.

What is the Bohlen-Pierce scale?

The Bohlen-Pierce scale divides the tritave (a 3:1 frequency ratio, or an octave plus a perfect fifth) into 13 equal steps of approximately 146.3 cents each. It produces a completely different harmonic landscape from octave-based systems, with its own set of consonances and dissonances.

How do I use the exported .scl file?

The .scl (Scala) format is supported by many software synthesizers and tuning utilities. You can load the file into instruments like Surge, ZynAddSubFX, Pianoteq, or use the free Scala application to convert it for other formats. Most DAWs support .scl via plugin tuning tables.

Is any data uploaded or recorded?

No. All scale computation, audio playback, and file export happens 100% locally in your browser using JavaScript and the Web Audio API. Nothing is sent to any server. The tool works completely offline once loaded.

What is the difference between EDO and just intonation?

EDO (equal division of the octave) spaces all steps uniformly so every fifth, third, or second of the same type is identical in size — making transposition easy. Just intonation (JI) uses small-integer frequency ratios (e.g. 3:2 for a perfect fifth, 5:4 for a major third) that are the purest sounding intervals acoustically, but each transposition to a new key produces slightly different interval sizes. EDOs like 31 and 53 are popular precisely because they approximate JI ratios very closely while still remaining transposable systems.

Can I use this tool to tune a real instrument or synth?

Yes, indirectly. Export the scale as a Scala .scl file and load it into a software instrument that supports Scala tuning — Surge XT, ZynAddSubFX, Pianoteq, and many Kontakt-based instruments all accept .scl files. For hardware synthesizers, you may need to convert the .scl file using the free Scala application or an MTS-ESP MIDI tuning plugin. Physical instruments without tuning-table support (standard piano, most fretted guitars) cannot be retuned this way — refrettable guitars and fretless instruments are different.

What is Slendro and how does it differ from Pelog?

Slendro is a 5-tone Indonesian gamelan tuning with roughly equal steps of around 240 cents — though actual gamelan sets vary significantly from instrument to instrument and no two are tuned identically. Pelog is a 7-tone system with very unequal step sizes, creating distinct large and small intervals. Both are non-octave-repeating in practice: the "octave" on a real gamelan is slightly stretched or compressed. The presets here use historically common cent approximations, not the tuning of any specific gamelan.

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