MIDI Note Number Calculator

Frequently Asked Questions

Why is middle C sometimes called C3 and sometimes C4?

MIDI fixes A4 = 69 but never standardised the octave label. This tool uses the scientific standard: C4 = MIDI 60. Check your DAW's convention if notes play an octave off.

What are MIDI notes 0 and 127?

Note 0 is C-1 (about 8.18 Hz, sub-audible) and 127 is G9 (about 12,544 Hz). The span comfortably exceeds a grand piano (MIDI 21 to 108).

Can I retune everything by changing the A4 reference?

Yes - changing the A4 reference scales all frequencies while note numbers stay fixed, exactly how a global master-tune control works.

Is this useful for sampler mapping?

Very - knowing a sample's root note number and frequency lets you set pitch-tracking and key zones correctly so a single recording transposes cleanly across a wide range.

What is the waveform period used for?

The period in milliseconds is the reciprocal of frequency. It tells you how long one complete cycle takes, useful for designing LFO sync or oscillator phase settings.

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Estimates for informational purposes only.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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How It Works

The MIDI protocol identifies every pitch with a single integer from 0 to 127. This calculator converts freely between three representations: the MIDI note number, the note name plus octave (like C4 or A#5), and the frequency in hertz. It works in both directions - type a MIDI number to get its name and pitch, or type a note name and octave to get its MIDI number and frequency.

Frequencies use twelve-tone equal temperament with an adjustable A4 reference (default 440 Hz), so the tool doubles as a tuning reference for synths, samplers, and notation software.

By the MIDI standard, note 69 is A4. The frequency of any MIDI note m is f = ref x 2^((m - 69) / 12). To name a number, the pitch class is m mod 12 (0 = C, 11 = B) and the octave is floor(m / 12) - 1, making middle C = MIDI 60 = C4.

Use Cases

MIDI note conversion is needed constantly in music production and development:

Mapping a multisampled instrument's root notes to the correct MIDI number for pitch-tracking

Debugging a MIDI controller that plays notes an octave higher or lower than expected

Scripting an arpeggiator pattern by note number rather than by name

Generating a test tone at a precise frequency from a known note name

Converting notation software output (which uses note names) to hardware synth addresses (which use numbers)

Tips

Middle C is MIDI 60 = C4 in this tool (and most DAWs), but some software labels the same note C3 or C5 - always verify the octave convention when troubleshooting.

C# and Db are the same MIDI number (enharmonic equivalents) - the protocol uses a single integer for each pitch.

MIDI 0 is C-1 (about 8.18 Hz, sub-audible) and MIDI 127 is G9 (about 12,544 Hz).

Changing the A4 reference scales all frequencies while note numbers stay fixed, matching a global master-tune control.

Pitch-bend and microtuning add a fractional offset on top of the integer note number.

FAQ

Why is middle C sometimes called C3 and sometimes C4?

MIDI fixes A4 = 69 but never standardised the octave label, so middle C is variously written C3, C4, or C5 by different manufacturers. This tool uses the scientific standard: C4 = MIDI 60.

What is MIDI 0 and MIDI 127?

Note 0 is C-1 (about 8.18 Hz, sub-audible) and 127 is G9 (about 12,544 Hz). This comfortably exceeds the span of a grand piano, which runs from MIDI 21 to 108.

Can I retune everything by changing the A4 reference?

Yes - change the A4 reference and every frequency scales together while note numbers stay fixed, exactly how a global master-tune control works.

Is this useful for sampler mapping?

Very - knowing a sample's root note number and frequency lets you set pitch-tracking and key zones correctly so a single recording transposes cleanly across a wide range.

What is the waveform period used for?

The period in milliseconds is the reciprocal of frequency. It tells you how long one complete cycle of the waveform takes, which is useful for designing LFO sync or oscillator phase settings.

MIDI Note Number Calculator

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