The hertz of piano keys are the measured frequencies for each key from A0 (≈27.50 Hz) up to C8 (≈4186.01 Hz)A4 = 440 Hz; these numbers tell you the exact cycles per second for every pitch on an 88-key piano.
Exact hertz map for every piano key (A0 → C8)
Below is a compact A0–C8 frequency list with note names, MIDI numbers, and Hz values (reference: A4 = 440 Hz). Middle C is C4 ≈ 261.63 Hz.
A0 (MIDI 21) — 27.50 Hz
A#0 / Bb0 (MIDI 22) — 29.14 Hz
B0 (MIDI 23) — 30.87 Hz
C1 (MIDI 24) — 32.70 Hz
C#1 / Db1 (MIDI 25) — 34.65 Hz
D1 (MIDI 26) — 36.71 Hz
D#1 / Eb1 (MIDI 27) — 38.89 Hz
E1 (MIDI 28) — 41.20 Hz
F1 (MIDI 29) — 43.65 Hz
F#1 / Gb1 (MIDI 30) — 46.25 Hz
G1 (MIDI 31) — 49.00 Hz
G#1 / Ab1 (MIDI 32) — 51.91 Hz
A1 (MIDI 33) — 55.00 Hz
A#1 / Bb1 (MIDI 34) — 58.27 Hz
B1 (MIDI 35) — 61.74 Hz
C2 (MIDI 36) — 65.41 Hz
C#2 / Db2 (MIDI 37) — 69.30 Hz
D2 (MIDI 38) — 73.42 Hz
D#2 / Eb2 (MIDI 39) — 77.78 Hz
E2 (MIDI 40) — 82.41 Hz
F2 (MIDI 41) — 87.31 Hz
F#2 / Gb2 (MIDI 42) — 92.50 Hz
G2 (MIDI 43) — 98.00 Hz
G#2 / Ab2 (MIDI 44) — 103.83 Hz
A2 (MIDI 45) — 110.00 Hz
A#2 / Bb2 (MIDI 46) — 116.54 Hz
B2 (MIDI 47) — 123.47 Hz
C3 (MIDI 48) — 130.81 Hz
C#3 / Db3 (MIDI 49) — 138.59 Hz
D3 (MIDI 50) — 146.83 Hz
D#3 / Eb3 (MIDI 51) — 155.56 Hz
E3 (MIDI 52) — 164.81 Hz
F3 (MIDI 53) — 174.61 Hz
F#3 / Gb3 (MIDI 54) — 185.00 Hz
G3 (MIDI 55) — 196.00 Hz
G#3 / Ab3 (MIDI 56) — 207.65 Hz
A3 (MIDI 57) — 220.00 Hz
A#3 / Bb3 (MIDI 58) — 233.08 Hz
B3 (MIDI 59) — 246.94 Hz
C4 (MIDI 60) — 261.63 Hz
C#4 / Db4 (MIDI 61) — 277.18 Hz
D4 (MIDI 62) — 293.66 Hz
D#4 / Eb4 (MIDI 63) — 311.13 Hz
E4 (MIDI 64) — 329.63 Hz
F4 (MIDI 65) — 349.23 Hz
F#4 / Gb4 (MIDI 66) — 369.99 Hz
G4 (MIDI 67) — 392.00 Hz
G#4 / Ab4 (MIDI 68) — 415.30 Hz
A4 (MIDI 69) — 440.00 Hz
A#4 / Bb4 (MIDI 70) — 466.16 Hz
B4 (MIDI 71) — 493.88 Hz
C5 (MIDI 72) — 523.25 Hz
C#5 / Db5 (MIDI 73) — 554.37 Hz
D5 (MIDI 74) — 587.33 Hz
D#5 / Eb5 (MIDI 75) — 622.25 Hz
E5 (MIDI 76) — 659.25 Hz
F5 (MIDI 77) — 698.46 Hz
F#5 / Gb5 (MIDI 78) — 739.99 Hz
G5 (MIDI 79) — 783.99 Hz
G#5 / Ab5 (MIDI 80) — 830.61 Hz
A5 (MIDI 81) — 880.00 Hz
A#5 / Bb5 (MIDI 82) — 932.33 Hz
B5 (MIDI 83) — 987.77 Hz
C6 (MIDI 84) — 1046.50 Hz
C#6 / Db6 (MIDI 85) — 1108.73 Hz
D6 (MIDI 86) — 1174.66 Hz
D#6 / Eb6 (MIDI 87) — 1244.51 Hz
E6 (MIDI 88) — 1318.51 Hz
F6 (MIDI 89) — 1396.91 Hz
F#6 / Gb6 (MIDI 90) — 1479.98 Hz
G6 (MIDI 91) — 1567.98 Hz
G#6 / Ab6 (MIDI 92) — 1661.22 Hz
A6 (MIDI 93) — 1760.00 Hz
A#6 / Bb6 (MIDI 94) — 1864.66 Hz
B6 (MIDI 95) — 1975.53 Hz
C7 (MIDI 96) — 2093.00 Hz
C#7 / Db7 (MIDI 97) — 2217.46 Hz
D7 (MIDI 98) — 2349.32 Hz
D#7 / Eb7 (MIDI 99) — 2489.02 Hz
E7 (MIDI 100) — 2637.02 Hz
F7 (MIDI 101) — 2793.83 Hz
F#7 / Gb7 (MIDI 102) — 2959.96 Hz
G7 (MIDI 103) — 3135.96 Hz
G#7 / Ab7 (MIDI 104) — 3322.44 Hz
A7 (MIDI 105) — 3520.00 Hz
A#7 / Bb7 (MIDI 106) — 3729.31 Hz
B7 (MIDI 107) — 3951.07 Hz
C8 (MIDI 108) — 4186.01 Hz
Quick reference callouts and tuning snippet
Middle C (C4) = 261.63 Hz; A0 = 27.50 Hz; C8 = 4186.01 Hz.
Common studio/orchestral anchors: A4 440 Hz, A4 442 Hz, and historical choices such as Baroque A ≈ 415 Hz or alternate A432; copy-paste tuning label for DAWs: A=440 Hz or A=442 Hz.
How to calculate any piano key’s frequency
Use the formula: f = 440 × 2^(n/12), where n is the number of semitones between the target note and A4 (MIDI 69). That gives exact Hz under equal temperament.
Example: C4 is 9 semitones below A4, so n = −9 and f = 440 × 2^(−9/12) ≈ 261.63 Hz.
Example: E4 is 5 semitones below A4, so n = −5 and f = 440 × 2^(−5/12) ≈ 329.63 Hz.
Example: A3 is 12 semitones below A4, so n = −12 and f = 440 × 2^(−12/12) = 220 Hz.
The semitone ratio is 2^(1/12) ≈ 1.059463; multiply or divide by that for single-semitone steps and double/halve the frequency for octaves.
Real-world pitch standards and concert pitch choices
A440 is the modern international standard for most classical and studio work; it gives consistent reference across instruments and digital projects.
A442 is common for orchestral tuning to brighten the ensemble; it raises every key by ~8 cents relative to A440 and requires agreement between players and recording engineers.
A432 and other alternative pitches are sometimes used for stylistic or preference reasons; they shift all frequencies downward and can clash with fixed-pitch instruments unless all parts are retuned.
Baroque ensembles often use ~415 Hz (about a semitone below A440) to match period instruments and historical practice.
Changing the reference A simply multiplies every Hz by the same factor (newA / 440) so all keys shift equally; coordinate the reference before rehearsal or recording.
Why measured Hz can differ from clean values: overtones and inharmonicity
Piano strings produce partials that are not exact integer multiples of the fundamental because of string stiffness; this phenomenon is called inharmonicity and it makes partials slightly sharp.
Inharmonicity alters perceived pitch, especially in the bass and high treble where stiffness and short string length shift partials more; tuners compensate rather than tuning strictly to equal-tempered Hz everywhere.
The aural result is that a “mathematically correct” frequency can sound thin or out of tune unless octaves are adjusted; that’s why technicians perform stretched tuning across registers.
Tuning practice and stretched tuning
Standard workflow: set reference A (usually A440 or conductor-specified A), tune A4 first, establish octave relationships outward, and apply stretch to upper and lower registers.
Tuners use beats between partials to line up perceived pitch; aural tuning uses intervals and beats, while strobe tuners or high-resolution electronic tuners give visual confirmation.
Environmental factors matter: temperature and humidity change string tension and soundboard dimensions; pitch can drift by several cents with room swings of a few degrees Celsius.
For performance venues, retune intervals depend on use: weekly for daily use in stable conditions, before each concert in variable settings, and after heating/cooling changes.
Measuring key frequencies: tuners, spectrum analyzers, apps, and MIDI tools
Best tools: mechanical or electronic strobe tuners for highest accuracy, high-quality chromatic tuners for quick checks, and spectrum analyzers for visual confirmation of fundamentals and partials.
Watch digital caveats: low sample rates or smartphone mics can introduce aliasing and inaccurate low-frequency readings; use interface or external mic for precise spectrum analysis.
To convert MIDI to Hz in a DAW use the same formula with MIDI number m: f = 440 × 2^((m − 69)/12); most DAWs expose a channel tuning or master pitch setting labeled simply as A = 440 or A = 442.
Digital pianos map samples to concert pitch by internally assigning each sample to a base MIDI note and using pitch-shift algorithms to achieve the target Hz; check the instrument’s reference pitch setting if things sound off.
Frequency extremes and perception
The lowest piano key, A0 ≈ 27.50 Hz, is often felt as much as heard because human hearing sensitivity drops off below ~60 Hz and room modes dominate low-frequency behavior.
The highest piano fundamental, C8 ≈ 4186.01 Hz, sits in a region where overtones contribute most to perceived brightness; many of the piano’s harmonics extend well above that, shaping tone more than the fundamental alone.
Room acoustics change perceived clarity and pitch perception; standing waves, furniture, and wall materials can emphasize or cancel frequencies and make precise tuning sound different in performance than in the practice room.
Practical uses for knowing exact Hz
Sampling: retune samples to concert pitch by calculating semitone offsets with the frequency formula or by resampling using the Hz ratio between original and target notes.
Synthesis: set oscillator frequencies directly using the formula or map MIDI notes to Hz in synth envelopes for exact tuning across voices.
Tuning other instruments and building reference tones: generate pure sine or piano-sample reference tones at target Hz for singers, ensembles, or click tracks.
Ear training: practice identifying octaves and intervals by listening for frequency ratios (octave = 2:1, perfect fifth ≈ 3:2 in just intonation but ~1.498 in equal temperament); use Hz anchors for precise interval drills.
Quick troubleshooting checklist when keys sound off-pitch
Cause: room temperature/humidity shift. Fix: re-check reference pitch and retune affected registers; allow instrument to acclimate after moving between environments.
Cause: dead or loose string or tuning pin. Fix: identify note with slow attack and weak sustain, call a technician for pin tightening or restringing; do not force full-tension fixes yourself.
Cause: perceived detune from inharmonicity. Fix: use a technician to apply a measured stretch; for quick checks use octave intervals and beat-rate listening to catch inconsistent stretch.
Immediate steps: verify the reference A with a stable tone, check octaves above and below A, then inspect affected keys for mechanical issues such as sticky action or muted strings.
Handy estimation tricks and rapid conversions
Octave rule: multiply/divide by 2 for each octave up/down. Semitone step: multiply/divide by approximately 1.05946 for each semitone.
Quick anchors: A4 = 440 Hz, C4 ≈ 261.63 Hz, G4 ≈ 392 Hz. Use these to approximate nearby notes on stage.
One-line MIDI-to-Hz formula: Hz = 440 × 2^((MIDI−69)/12). One-line Hz-to-MIDI estimate: MIDI ≈ 69 + 12 × log2(Hz/440).
Printable gig-cheat: list quick anchors (A4, C4, A3, A5) and the semitone multiplier rounded to 1.05946 for on-the-fly pitch math.
Frequently asked micro-questions
Is Middle C 256 Hz or 261.63 Hz? C4 = 261.63 Hz under A440 equal temperament; 256 Hz appears in alternate “scientific pitch” systems where A is set differently.
Can you tune to A432? Yes; tuning to A432 simply scales every frequency so A4 = 432 Hz and all keys shift down by the ratio 432/440.
What’s the difference between Hz and pitch names? Hz measures cycles per second; pitch names (for example, C4, A4) map to specific Hz values depending on the chosen reference frequency.
Quick reference appendix: essential formulas and printable snippet
Core formulas: Hz = 440 × 2^((m − 69)/12) (m = MIDI note), semitone ratio 2^(1/12) ≈ 1.059463, octave factor = 2.
Mini printable frequency excerpt: A0 27.50 Hz, C2 65.41 Hz, C3 130.81 Hz, C4 261.63 Hz, A4 440.00 Hz, C5 523.25 Hz, C6 1046.50 Hz, C7 2093.00 Hz, C8 4186.01 Hz.
Licensing-friendly tip: embed the numeric table above into lesson PDFs or studio templates without copyrighted artwork; include a short note that values assume equal temperament with the chosen A reference.
LSI terms used across this guide include: piano key frequencies, MIDI note mapping, Hz lookup, concert pitch, frequency formula, semitone interval, pitch calculation, strobe tuner, and frequency analyzer.
