MIDI Note to Frequency Converter

MIDI (Musical Instrument Digital Interface) uses numbers 0-127 to represent musical notes, with Middle C typically assigned to note 60. Understanding the relationship between MIDI notes and frequencies is essential for synthesizer programming, sound design, and electronic music production.

The MIDI Note System

MIDI divides the audible frequency spectrum into 128 notes, numbered 0 to 127. Each number represents a specific pitch, with middle C (C4) traditionally assigned to MIDI note 60. This standardization allows electronic instruments and software to communicate pitch information universally.

Important MIDI Note References

• C-1 (MIDI 0): 8.176 Hz - Below human hearing threshold
• C0 (MIDI 12): 16.352 Hz - Lowest C on most synthesizers
• C1 (MIDI 24): 32.703 Hz - Sub-bass frequencies
• C2 (MIDI 36): 65.406 Hz - Low bass range
• C3 (MIDI 48): 130.813 Hz - Bass guitar range
• C4 (MIDI 60): 261.626 Hz - Middle C
• A4 (MIDI 69): 440 Hz - Concert pitch reference
• C5 (MIDI 72): 523.251 Hz - Soprano range
• C8 (MIDI 108): 4186.009 Hz - Highest C on piano
• G9 (MIDI 127): 12543.854 Hz - Highest MIDI note

The Mathematics Behind the Conversion

The frequency of any MIDI note is calculated using the equal temperament formula:

f = 440 × 2^((n-69)/12)

Where:

• f = frequency in Hz
• n = MIDI note number
• 440 = A4 reference frequency (can be adjusted)
• 69 = MIDI note number for A4
• 12 = number of semitones in an octave

Tuning Standards Explained

A440 (Standard Tuning): The international standard since 1955, with A4 = 440 Hz. Used in most modern music production.

A432 (Verdi Tuning): Advocated by some as more "natural" or "harmonious." Popular in certain new age and meditation music circles.

A442 (European Tuning): Common in many European orchestras, slightly brighter than A440.

A415 (Baroque Tuning): Historical tuning used for period-correct performances of Baroque music, approximately one semitone lower than modern tuning.

Practical Applications in Electronic Music

Synthesizer Programming: Knowing exact frequencies helps when:

• Setting oscillator frequencies manually
• Creating precise detuning for chorus effects
• Programming FM synthesis ratios
• Designing custom wavetables

Mixing and EQ: Understanding note frequencies aids in:

• Identifying and removing resonant frequencies
• Finding the fundamental frequency of bass notes
• Creating space in the mix through frequency separation
• Tuning resonant filters musically

Sound Design: Frequency knowledge is crucial for:

• Creating harmonic and inharmonic timbres
• Designing kick drums tuned to the key of the song
• Building chord stacks from individual oscillators
• Creating microtonal and experimental tunings

Frequency Ranges in Electronic Music

• Sub-Bass (20-60 Hz): Felt more than heard, crucial for club systems
• Bass (60-250 Hz): Foundation of most electronic music
• Low-Mids (250-500 Hz): Body and warmth of sounds
• Midrange (500-2000 Hz): Most melodic content lives here
• Upper-Mids (2-4 kHz): Presence and definition
• Highs (4-20 kHz): Brightness, air, and sparkle

Tips for Using This Calculator

• Use it to find the exact frequency when tuning oscillators in analog synths
• Reference it when setting up frequency-based effects like ring modulators
• Calculate harmonic relationships for additive synthesis
• Determine filter cutoff frequencies that align with musical notes
• Find the frequencies of problem notes when mixing
• Convert between different tuning standards for collaborative projects

Why does middle C have different MIDI numbers in different software?

While MIDI note 60 is the standard for middle C, some manufacturers (notably Yamaha) use different octave numbering systems. Always check your software's documentation. The frequency (261.626 Hz at A440) remains constant regardless of the numbering system.

What's the audible range of MIDI notes?

Human hearing typically ranges from 20 Hz to 20,000 Hz. This corresponds roughly to MIDI notes 12 (C0 at 16.35 Hz) to 127 (G9 at 12,543 Hz). Notes below MIDI 12 are felt as vibrations rather than heard as pitches.

How does detuning affect frequency?

Each cent (1/100th of a semitone) represents approximately a 0.06% change in frequency. Detuning by ±5-10 cents creates subtle chorusing, while ±20-50 cents produces more obvious detuning effects.

Why use different tuning standards?

Different tuning standards serve various purposes: A432 is claimed to be more harmonious with nature, A442 provides extra brilliance for orchestras, and historical tunings like A415 are used for authentic period performances.

How do I use this for FM synthesis?

In FM synthesis, carrier and modulator frequency ratios determine the timbre. Use this calculator to find exact frequencies, then calculate ratios. Integer ratios (2:1, 3:2) produce harmonic sounds, while non-integer ratios create inharmonic, bell-like tones.

What's the difference between period and wavelength?

Period is the time it takes for one complete wave cycle (measured in milliseconds), while wavelength is the physical distance of one wave cycle in air (measured in meters). Lower frequencies have longer periods and wavelengths. For example, a 100 Hz bass note has a wavelength of about 3.43 meters.

Can I use frequencies between MIDI notes?

Absolutely! While MIDI uses discrete semitone steps, actual frequencies exist on a continuum. Pitch bend, portamento, and microtuning allow access to frequencies between standard MIDI notes. Some synthesizers support MIDI Tuning Standard (MTS) for microtonal scales and alternative tuning systems beyond 12-tone equal temperament.

Confusing Octave Numbering Systems

Different manufacturers and DAWs use different octave numbering conventions. Some call middle C "C3," others "C4," and Yamaha uses "C5." This doesn't change the actual frequency or MIDI note number – it's purely a display preference. Always verify your system's octave numbering when communicating pitch information or programming synthesizers from documentation.

Ignoring Nyquist Frequency Limitations

When working with high-frequency oscillators, remember the Nyquist theorem: your sample rate must be at least twice the highest frequency you want to reproduce. At 44.1kHz sample rate, frequencies above 22.05kHz will alias and create artifacts. Higher MIDI notes (above MIDI 108) can produce overtones beyond the Nyquist frequency, causing unwanted aliasing distortion.

Overlooking Sub-Bass Tuning

Many producers don't realize their kick drums and sub-bass are detuned from the track's key. Use this calculator to tune these elements to the root note or fifth of your song's key for maximum clarity and power. A kick drum tuned to the wrong frequency can clash with the bassline and create a muddy low end.

Not Accounting for Tuning Standard Differences

Mixing projects with different tuning standards (A440 vs A432) creates subtle but noticeable beating and dissonance. Ensure all elements in your project use the same reference tuning. This is especially important when working with sampled instruments or collaborating with other producers.

Forgetting About Harmonics

Every note produces harmonics at integer multiples of the fundamental frequency. When applying distortion or saturation, these harmonics become more prominent. Make sure you have headroom in your frequency spectrum, or high-frequency harmonics can cause harshness and digital clipping in your mix.

FM Synthesis Ratio Programming

Frequency Modulation synthesis relies on mathematical relationships between carrier and modulator frequencies. Simple integer ratios (1:1, 2:1, 3:2) produce harmonic, musical timbres. A carrier at 440 Hz (A4) with a modulator at 880 Hz (2:1 ratio) creates even-order harmonics. Experimenting with ratios like 1.41:1 or 2.73:1 produces metallic, bell-like inharmonic spectra. Use this calculator to determine exact frequencies for each operator in your FM patches.

Additive Synthesis Harmonic Stacking

In additive synthesis, complex timbres are built by combining sine waves at different frequencies. Calculate the fundamental frequency, then add harmonics at integer multiples: 2x, 3x, 4x, etc. The amplitude and phase of each harmonic determines the final timbre. For example, a sawtooth wave contains all harmonics with amplitudes inversely proportional to their harmonic number (1/n). Understanding these frequency relationships helps you recreate classic waveforms or design entirely new timbres.

Resonant Filter Musical Tuning

Resonant filters become self-oscillating at high resonance settings, essentially acting as sine wave oscillators. Tune these resonances to musical intervals by setting the cutoff frequency to specific note frequencies. Create evolving textures by automating filter cutoffs through a scale's note frequencies. Some classic analog synthesizers (like the TB-303) are beloved specifically for their musically-tuned resonant filters.

Microtonal and Alternative Tuning Systems

Move beyond standard 12-tone equal temperament by using exact frequency ratios. Just intonation uses pure frequency ratios like 3:2 (perfect fifth) and 5:4 (major third), producing consonance impossible in equal temperament. Explore quarter-tone scales (24 notes per octave), Bohlen-Pierce scales (13 divisions), or xenharmonic tunings. Modern software synthesizers often support MTS (MIDI Tuning Standard) for loading custom scales. Use frequency calculations to design your own microtonal systems.

Ring Modulation Frequency Selection

Ring modulation creates sum and difference frequencies from two inputs. If you modulate a 440 Hz carrier with a 100 Hz modulator, you get sidebands at 540 Hz and 340 Hz. Calculate these frequency relationships to predict the output spectrum. Musical ring modulation uses harmonically-related frequencies, while dissonant effects come from non-harmonic combinations. This principle also applies to amplitude modulation (AM) synthesis.

Waveshaping and Distortion Harmonics

Different waveshaping algorithms generate specific harmonic series. Soft clipping produces primarily odd harmonics (3rd, 5th, 7th), while hard clipping generates all harmonics. Knowing the fundamental frequency helps predict where these harmonics will appear in your mix. A 100 Hz bass note hard-clipped will produce harmonics at 200 Hz, 300 Hz, 400 Hz, etc. Design your waveshaping to complement rather than clash with other mix elements.

Finding Problem Frequencies in Mixes

When a note sounds muddy or harsh, convert its MIDI number to frequency to identify the problem area. If a C2 bass note (65.4 Hz) sounds boomy, check for room modes or excessive energy around that frequency. Use narrow EQ cuts at the calculated frequency and its octaves to clean up resonances. This targeted approach is more effective than broad EQ sweeps.

Tuning Kick Drums to Your Track

Professional electronic music producers tune kick drums to the key of their tracks. Calculate the frequency of your song's root note, then tune your kick's fundamental to match. For a track in E minor, tune your kick to MIDI 40 (E1 at 41.2 Hz) or MIDI 28 (E0 at 20.6 Hz) for maximum low-end power and clarity. This creates harmonic alignment between the rhythm and melodic elements.

Creating Frequency Gaps for Clarity

Understanding exact note frequencies helps you carve spaces in busy mixes. If your lead plays primarily around A4 (440 Hz), high-pass filter your pads above 400 Hz to create separation. Calculate the frequency ranges of each element and intentionally place them in different spectral regions. This frequency-conscious arrangement prevents masking and creates professional-sounding mixes without excessive EQ.

Harmonic Layering for Fat Bass Sounds

Layer multiple oscillators at octave relationships for massive bass tones. A fundamental at 55 Hz (A1), octave at 110 Hz (A2), and another at 220 Hz (A3) creates a full-spectrum bass. Add slight detuning (±5-10 cents) between layers for movement and width. This technique works because our brains perceive these octave relationships as a single, fat sound rather than separate notes.

Sidechain Compression with Musical Timing

While primarily tempo-based, sidechain compression interacts with note frequencies. Fast release times (10-30ms) can create rhythmic pumping that emphasizes certain frequencies. If your sidechain release time matches the period of a bass note (e.g., 20ms for 50 Hz), it can reinforce or cancel that frequency. Be aware of this interaction when crafting your sidechain settings.