Semitone Calculator
Calculate pitch distance, intervals, cents, octaves, and transposition.
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Frequency calculations use 12-tone equal temperament. One semitone equals 100 cents and 12 semitones equal one octave.
Arbitrary frequencies can be a fractional number of semitones apart, so frequency results are not forced to whole-note values.
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Calculate Semitones Between Notes, Frequencies, and Pitch Changes
The Semitone Calculator helps you measure the exact pitch distance between two notes or frequencies and can also transpose a note or frequency by a chosen number of semitones.
You can use it to answer questions such as:
- How many semitones are between C4 and G4?
- How many cents separate two frequencies?
- What note is 7 semitones above A3?
- What frequency results from shifting 440 Hz down 3 semitones?
- How many octaves does a pitch change represent?
The calculator uses 12-tone equal temperament (12-TET) and supports note-to-note calculations, frequency-to-frequency calculations, and transposition.
If you are working with raw frequency values and need to identify a note first, use the Hz to Note Converter. To convert a musical note back into Hertz, use the Note to Frequency Converter.
How to Use the Semitone Calculator
Choose the mode that matches what you want to calculate.
Note to Note
Select a starting note and ending note, including their octaves.
For example:
C4 → G4
The calculator can return:
- 7 semitones
- 700 cents
- a perfect fifth
- upward direction
- the related start and end frequencies
This mode is useful when comparing melodies, vocal notes, chord tones, or transposed passages.
Frequency to Frequency
Enter two positive frequency values in Hertz.
For example:
220 Hz → 440 Hz
The difference is:
- 12 semitones
- 1200 cents
- 1 octave
Unlike note-based calculations, frequency inputs can produce fractional semitone values when the frequencies do not align exactly with equal-tempered notes.
Transpose by Semitones
Enter a starting note or frequency and choose how many semitones you want to move.
Positive values transpose upward. Negative values transpose downward.
For example:
C4 + 7 semitones = G4
or:
440 Hz – 3 semitones ≈ 369.99 Hz
What Is a Semitone?
A semitone is the smallest standard interval in 12-tone equal temperament. It is also commonly called a half step.
On a piano, moving from one key to the immediately adjacent key—black or white—is one semitone.
Examples include:
- C to C# = 1 semitone
- E to F = 1 semitone
- B to C = 1 semitone
- C to D = 2 semitones
- C to G = 7 semitones
- C to the next C = 12 semitones
Twelve semitones make one octave.
If octave distance is the main measurement you need, the Octave Calculator can give you a more focused result.
How Semitone Distance Is Calculated
For frequencies, semitone distance is based on the ratio between the two frequencies.
The formula is:
Semitones = 12 × log₂(f₂ / f₁)
where:
f₁is the starting frequency;f₂is the ending frequency.
If the second frequency is exactly double the first, the calculation gives 12 semitones, or one octave.
For example:
220 Hz → 440 Hz
The ratio is 2:1, so the result is exactly 12 semitones.
The calculator keeps decimal precision when two arbitrary frequencies do not correspond to a whole number of semitones.
Semitones vs Cents
A cent is a smaller unit of musical pitch.
In 12-tone equal temperament:
- 1 semitone = 100 cents
- 2 semitones = 200 cents
- 7 semitones = 700 cents
- 12 semitones = 1200 cents
Cents are especially useful when the pitch difference is smaller than one semitone.
For example, a singer may be 15 cents flat while still clearly singing the same named note. This is why tools such as the Vocal Pitch Monitor show cents deviation instead of only displaying the nearest note.
The relationship is simple for equal-tempered note intervals, but frequency-to-frequency calculations can produce values such as 36.4 cents or 247.8 cents.
Semitones vs Whole Tones
A whole tone, also called a whole step, contains two semitones.
For example:
- C to C# = 1 semitone
- C to D = 2 semitones, or 1 whole tone
- D to E = 2 semitones
- E to F = only 1 semitone
This pattern is important when reading scales because not every adjacent letter name is separated by the same number of semitones.
Semitones and Octaves
An octave contains 12 semitones.
That gives a simple relationship:
| Semitones | Octave Distance |
|---|---|
| 6 | 0.5 octave |
| 12 | 1 octave |
| 18 | 1.5 octaves |
| 24 | 2 octaves |
| 36 | 3 octaves |
A shift of +12 semitones keeps the same pitch class while moving the note one octave higher.
For example:
A3 + 12 semitones = A4
A shift of -12 semitones moves one octave lower.
This relationship is useful for singers comparing range measurements from tools such as the Vocal Range Calculator.
Common Musical Intervals by Semitone Count
The semitone count also corresponds to common interval sizes.
| Semitones | Common Interval |
|---|---|
| 0 | Unison |
| 1 | Minor second |
| 2 | Major second |
| 3 | Minor third |
| 4 | Major third |
| 5 | Perfect fourth |
| 6 | Tritone |
| 7 | Perfect fifth |
| 8 | Minor sixth |
| 9 | Major sixth |
| 10 | Minor seventh |
| 11 | Major seventh |
| 12 | Octave |
This table is useful for quick reference, but interval naming can depend on note spelling.
For example, C to D# and C to Eb cover the same number of semitones in 12-TET, yet they can be described differently in traditional music theory because the note names are spelled differently.
The calculator therefore treats semitone distance as the primary mathematical result and interval labels as musical context.
Sharps, Flats, and Enharmonic Notes
Some pitches can be written with more than one note name.
Examples include:
- C# = Db
- D# = Eb
- F# = Gb
- G# = Ab
- A# = Bb
These are called enharmonic equivalents in 12-tone equal temperament because they represent the same equal-tempered pitch while using different note spellings.
A sharps/flats display option is useful when the preferred spelling depends on the key or musical context.
For example, a note might be more naturally written as Bb in one key and A# in another, even though both map to the same equal-tempered frequency.
Transposing Notes by Semitones
Transposition means moving a note or passage higher or lower while preserving the pitch relationships.
For example:
C4 + 4 semitones = E4
E4 – 2 semitones = D4
A3 + 12 semitones = A4
Semitone-based transposition is useful when:
- changing a song to a more comfortable singing key;
- moving a melody into another register;
- matching an instrument to a vocal part;
- testing alternate pitch ranges;
- comparing notes in different octaves.
If you want to hear or inspect the note after transposition, the Pitch Detector can help verify a live note from your microphone.
Transposing Frequencies
Frequency transposition follows an exponential relationship rather than simple addition.
The formula is:
New Frequency = Starting Frequency × 2^(n/12)
where n is the semitone shift.
For example, shifting a frequency up 12 semitones doubles it.
220 Hz + 12 semitones = 440 Hz
Moving down 12 semitones halves it.
440 Hz – 12 semitones = 220 Hz
This is why adding a fixed number of Hertz is not the correct way to transpose by a musical interval.
Practical Uses for Singers and Musicians
A Semitone Calculator is useful anywhere you need to compare or shift pitch precisely.
Singers can calculate the distance between their lowest and highest notes, compare target notes, or understand how far a song would need to be transposed to sit more comfortably.
If you are measuring your voice directly, the Voice Frequency Test can provide frequency data, while the Voice Analyzer provides a broader set of live vocal measurements.
Musicians can use semitone distance to study intervals, transpose melodies, compare note relationships, and understand how octave shifts affect frequency.
The same mathematics is also useful in audio production, where pitch-shifting controls are frequently expressed in semitones.
Accuracy and Tuning Assumptions
The calculator assumes 12-tone equal temperament.
It also uses an A4 tuning reference for note-to-frequency calculations, with 440 Hz as the standard default unless another reference value is selected.
That assumption matters because musical tuning systems are not universally identical. Historical tuning systems, just intonation, microtonal music, or ensembles using another concert-pitch reference may produce different frequency values.
For frequency inputs, the mathematical semitone distance can still be calculated precisely from the ratio between frequencies, even when those frequencies do not fall exactly on standard equal-tempered notes.
The calculator should therefore not be interpreted as saying that every musical tradition or tuning system divides pitch into the same intervals.
Frequently Asked Questions
How many semitones are in an octave?
There are 12 semitones in one octave in 12-tone equal temperament.
Is a semitone the same as a half step?
Yes. In common Western music terminology, a semitone and a half step usually refer to the same pitch distance.
How many cents are in one semitone?
One equal-tempered semitone contains 100 cents.
How many semitones are in a whole step?
A whole step, or whole tone, contains two semitones.
How many semitones are between C and G?
Ascending from C to G is seven semitones, which corresponds to a perfect fifth in that spelling.
What does +12 semitones mean?
It means transposing a pitch upward by one octave.
What does -12 semitones mean?
It means moving the pitch down by one octave.
How do you calculate semitones between two frequencies?
Use the frequency ratio formula 12 × log₂(f₂ / f₁). The result can be a whole or fractional number of semitones.
Are C# and Db the same note?
In 12-tone equal temperament, C# and Db have the same equal-tempered pitch and frequency, but their musical spelling and theoretical function can differ.
Can I calculate semitones from my singing voice?
Yes. First determine the relevant notes or frequencies from your voice, then compare them with the calculator. A tool such as the Vocal Pitch Monitor can help identify live singing pitches before you calculate their distance.
Continue Exploring Pitch, Notes, and Vocal Range
Semitones provide a useful bridge between musical notes and measurable frequency.
Once you know the semitone distance, you can express the same change in cents, identify its octave relationship, calculate a transposed note, or determine the corresponding frequency ratio.
For note and frequency conversion, continue with the Hz to Note Converter or Note to Frequency Converter. For live vocal measurements, use the Voice Frequency Test or Voice Analyzer. If your goal is to understand the total pitch span of your singing voice, use the Vocal Range Calculator.
Together, these tools make it easier to move between notes, frequencies, intervals, semitones, cents, and octaves without treating them as separate concepts.