Enter a frequency in Hz to find the nearest musical note and see exactly how many cents sharp or flat it is from that note.
Useful for tuning by ear against a frequency counter, checking a synth oscillator, or identifying a hum or drone by pitch.
Frequency to Note
Frequency (Hz):
Reference A4 (Hz):
Nearest Note: —
Offset: —
How This Identifier Works
Every musical note corresponds to a specific frequency once a reference pitch (usually A4 = 440 Hz) is set. This tool converts your entered frequency into semitones above or below that reference, rounds to the nearest note, and reports the remaining difference in cents (100 cents = 1 semitone).
How to Use This Calculator
- Frequency (Hz): the pitch you want to identify.
- Reference A4: the tuning standard to measure against; defaults to 440 Hz if left blank.
- Click Identify Note to see the nearest note and how far off it is in cents.
Example: 445 Hz against a 440 Hz reference identifies as A4, about +19.6 cents sharp.
The Formulas and Worked Examples
Semitones from A4 = 12 × log₂(f ÷ A4). Round to the nearest whole number to get the note, and the leftover fraction × 100 gives the cents: cents = 1200 × log₂(f ÷ A4) measured from the nearest note.
Example 1: 220 Hz is exactly one octave below 440 Hz, so it is A3 with 0 cents of offset. Example 2: 261.63 Hz is 9 semitones below A4, which makes it C4 (middle C). Example 3: 445 Hz is about 19.6 cents above A4, which is noticeably sharp.
Where This Is Useful
Musicians, sound designers, and hobbyists use frequency readings from spectrum analyzers, tuner apps, and synth displays. Converting a raw Hz value to a note name and cents makes it easy to check that an instrument is in tune, identify the pitch of a hum or alarm, or tune a synth oscillator by numbers rather than by ear.
Did You Know?
- Most listeners can detect a pitch difference of around 5 to 10 cents, so anything within a few cents of a note generally reads as “in tune.”
- Some orchestras tune to A4 = 442 Hz or higher for a brighter sound, which shifts every note’s exact frequency slightly compared to the 440 Hz standard.
Frequently Asked Questions
What is a cent in music tuning?
A cent is 1/100th of a semitone. It’s the standard unit for describing small tuning differences that are too fine to express as a note name alone.
Why would I change the reference A4?
If you’re working with an ensemble or recording tuned to a non-standard reference, like 442 Hz, entering that reference gives you an accurate note match for that specific tuning system.
How accurate does my frequency reading need to be?
One decimal place is plenty for tuning. Near A4, 1 Hz is about 4 cents, so a reading that is off by a few Hz can change the cents result noticeably.
What does a negative offset mean?
A negative number means the pitch is flat, below the nearest note. A positive number means it is sharp, above the note.