Frequency to Note Converter

Convert sound frequencies to musical notes and calculate cents deviation. Essential for instrument tuning, audio production, and understanding musical pitch relationships.

Frequency (Hz)

A4 Reference (Hz)

440 Hz (Standard)

432 Hz (Alternative)

442 Hz (High)

About Frequency to Note Converter

Musical Pitch and Frequency

The relationship between musical notes and frequencies is fundamental to understanding sound and music theory. Every musical note corresponds to a specific frequency of sound waves, measured in Hertz (Hz). The standard reference point in modern Western music is A4 (concert pitch) at 440 Hz, established by the International Organization for Standardization (ISO) in 1975.

Understanding the Math

Mathematical Foundation:

Each octave represents a doubling of frequency
12 semitones divide each octave logarithmically
The frequency ratio between adjacent semitones is ¹²√2 (approximately 1.059463)
Cents measure microtuning: 100 cents = 1 semitone

The formula to calculate the number of semitones from A4 (440 Hz) is:

semitones = 12 × log₂(frequency / 440)

Musical Notes and Octaves

Note	Frequency (Hz)	Octave
A4	440.00	4
Middle C (C4)	261.63	4
C5	523.25	5

Understanding Cents

Cents Explained:

1 cent = 1/100th of a semitone
1200 cents = one octave
Positive cents indicate sharp tuning
Negative cents indicate flat tuning

Human Perception:

Most people can detect ~5-6 cents difference
Trained musicians: ~2-3 cents
Professional tuners: ~1 cent

Tuning Systems

Equal Temperament:

Modern standard tuning
Octave divided into 12 equal parts
All keys equally (slightly) out of tune
Enables modulation between keys

Historical Tunings:

Just Intonation: pure intervals
Pythagorean tuning: based on perfect fifths
Mean-tone temperament
Well temperament (Bach era)

Applications and Uses

Professional Uses:

Instrument tuning and calibration
Sound synthesis and electronic music
Audio engineering and production
Acoustic analysis and research

Educational Uses:

Music theory education
Ear training and development
Understanding harmonic relationships
Scientific demonstrations

Frequently Asked Questions

What is A4 reference tuning?

A4 (the A above middle C) is the standard pitch reference for musical tuning. The international standard is 440 Hz, though some musicians prefer alternative tunings like 432 Hz or 442 Hz. The choice of reference pitch affects the absolute frequency of all other notes while maintaining their relative relationships.

How are musical notes related to frequency?

In the Western musical system, each octave is divided into 12 semitones. The frequency ratio between any two adjacent semitones is the twelfth root of 2 (approximately 1.059463). This means that to go up one octave (12 semitones), you multiply the frequency by 2. For example, if A4 is 440 Hz, then A5 is 880 Hz.

What is a cent and how is it measured?

A cent is a unit of measure for musical intervals. One semitone is divided into 100 cents, making an octave 1200 cents. Cents are useful for describing very small pitch differences. The formula for cents deviation is: cents = 1200 × log₂(f₁/f₂), where f₁ and f₂ are the two frequencies being compared.

What is MIDI note number?

MIDI note numbers are a standard way of representing musical notes in digital systems. Middle C (C4) is MIDI note 60, and A4 (440 Hz) is MIDI note 69. Each semitone increases or decreases the MIDI note number by 1. This system is widely used in electronic music, synthesizers, and digital audio workstations.

Learn More

Musical Tuning Systems UNSW Music Acoustics

Share This Calculator

Include calculator values in URL

Embed on Your Website

Add this calculator to your website