Music Frequency to Note Converter
Practice and calculate music frequency note with our free tool. Includes worked examples, visual aids, and learning resources.
Formula
MIDI = 69 + 12 x log2(Frequency / Reference A4)
Where Frequency is the input in Hz and Reference A4 is the tuning standard (default 440 Hz). The note name and octave are derived from the MIDI number. Cents deviation measures the fractional semitone difference between the input frequency and the nearest note.
Worked Examples
Example 1: Identifying an Unknown Frequency
Problem: A tuner reads a frequency of 329.63 Hz from a guitar string. Identify the note, its octave, and any cents deviation from standard tuning at A4 = 440 Hz.
Solution: Semitones from A4 = 12 x log2(329.63 / 440) = 12 x log2(0.749) = 12 x (-0.4167) = -5.0\nMIDI note = 69 + (-5) = 64 = E4\nExact frequency of E4 = 440 x 2^(-5/12) = 329.628 Hz\nCents deviation = (329.63 - 329.628) / 329.628 x 1731 = +0.01 cents\nWavelength = 343 / 329.63 = 1.041 meters
Result: Note: E4 | MIDI: 64 | Deviation: +0.01 cents (in tune) | Wavelength: 104.1 cm
Example 2: Converting Between Tuning Standards
Problem: An orchestra tunes to A4 = 443 Hz. What frequency should a violinist play for middle C (C4) in this tuning system?
Solution: C4 is 9 semitones below A4\nMIDI note of C4 = 60, A4 = 69, difference = -9 semitones\nFrequency = 443 x 2^(-9/12)\nFrequency = 443 x 2^(-0.75)\nFrequency = 443 x 0.5946\nFrequency = 263.42 Hz\nCompared to standard: 261.63 Hz (A4=440), difference = +1.79 Hz
Result: C4 at A4=443 Hz tuning: 263.42 Hz (1.79 Hz higher than standard C4 at 261.63 Hz)
Frequently Asked Questions
How does frequency relate to musical pitch?
Frequency and musical pitch are directly related through a logarithmic relationship. Higher frequencies produce higher-pitched sounds, and the relationship between notes follows a geometric progression. In the Western equal temperament tuning system, each octave represents a doubling of frequency, and each semitone represents a frequency ratio of the twelfth root of 2, approximately 1.05946. This means that A4 at 440 Hz leads to A5 at 880 Hz and A3 at 220 Hz. The logarithmic nature of pitch perception means that humans perceive equal ratios of frequency as equal intervals of pitch, which is why doubling a frequency always sounds like the same musical interval regardless of the starting point.
What is MIDI note number and how does it relate to frequency?
MIDI (Musical Instrument Digital Interface) assigns a number from 0 to 127 to each musical note, with middle C defined as MIDI note 60 and A4 as MIDI note 69. The formula to convert MIDI note number to frequency is frequency equals 440 times 2 raised to the power of (MIDI note minus 69) divided by 12. Conversely, to convert frequency to MIDI note number, the formula is MIDI equals 69 plus 12 times the base-2 logarithm of frequency divided by 440. MIDI note 0 corresponds to C-1 at approximately 8.18 Hz, and MIDI note 127 corresponds to G9 at approximately 12,543.85 Hz. The MIDI system only represents discrete semitones, so pitch bend messages are used for continuous pitch control between notes.
What frequency range can human ears detect?
The typical range of human hearing spans from approximately 20 Hz to 20,000 Hz, though this varies significantly with age and individual sensitivity. Low-frequency hearing extends down to about 20 Hz, which corresponds roughly to the lowest note on a piano (A0 at 27.5 Hz). High-frequency sensitivity decreases substantially with age due to presbycusis, with many adults losing the ability to hear above 15,000 Hz by middle age. The most sensitive frequency range for human hearing is between 2,000 and 5,000 Hz, which corresponds to the upper register of the human voice. Musical instruments span a wide range: a piano covers 27.5 Hz to 4,186 Hz in fundamental frequencies, while harmonics extend much higher. Bass frequencies below 80 Hz are often felt physically as much as they are heard.
What is the relationship between wavelength and frequency?
Wavelength and frequency are inversely proportional, connected by the speed of sound. The formula is wavelength equals speed of sound divided by frequency. At room temperature of about 20 degrees Celsius, the speed of sound in air is approximately 343 meters per second. This means A4 at 440 Hz has a wavelength of about 78 centimeters, while low C2 at 65.4 Hz has a wavelength of about 5.24 meters, and high C8 at 4186 Hz has a wavelength of only about 8.2 centimeters. Wavelength is important for understanding room acoustics, speaker placement, and instrument design. Instruments that produce low frequencies require longer resonating bodies, which is why a bass guitar has longer strings than a regular guitar and why organ pipes for low notes can be over 10 meters long.
How do harmonics and overtones relate to fundamental frequency?
The fundamental frequency is the lowest frequency produced by a vibrating object and determines the perceived pitch of the note. Harmonics are integer multiples of the fundamental: the second harmonic is twice the fundamental, the third is three times, and so on. Overtones are all frequencies above the fundamental, which may or may not be harmonic depending on the instrument. A guitar string vibrating at 110 Hz (A2) produces harmonics at 220 Hz (A3), 330 Hz (E4), 440 Hz (A4), 550 Hz (C#5), and so forth. The relative strength of these harmonics defines the timbre or tonal color that distinguishes different instruments playing the same note. A clarinet emphasizes odd harmonics while a violin has a rich spectrum of both odd and even harmonics.
What formula does Music Frequency to Note Converter use?
The formula used is described in the Formula section on this page. It is based on widely accepted standards in the relevant field. If you need a specific reference or citation, the References section provides links to authoritative sources.