Vinyl RPM Pitch Shift Calculator
Calculate the pitch shift in cents when a vinyl record plays at a speed different from its nominal RPM. Useful for turntable calibration.
How to use this tool
- Enter nominal rpm and actual rpm in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your pitch shift and the full breakdown beneath it.
Find out how much pitch shift results from a turntable running slightly off speed.
Formula
Speed ratio = actual RPM ÷ nominal RPM
Pitch shift (¢) = 1200 × log2(speed ratio)
Semitones = pitch shift (¢) ÷ 100
Speed error (%) = (speed ratio − 1) × 100
How it works
This calculator determines the pitch shift introduced when a record plays at a slightly different speed than intended. Because pitch is proportional to playback speed, the frequency ratio between actual and nominal speed directly gives the musical interval in cents via the standard logarithmic pitch formula.
A speed error of about +3.5% raises pitch by roughly one semitone. Results are accurate for steady-state speed deviations; they do not model wow (slow speed fluctuation) or flutter (fast fluctuation), which cause pitch to vary continuously.
Worked example
Worked example
- Nominal RPM = 33.33, actual RPM = 33.33.
- Speed ratio = 33.33 / 33.33 = 1.0 (exact match).
- Pitch shift = 1200 × log₂(1) = 1200 × 0 = 0 ¢.
- Speed error = (1 − 1) × 100 = 0 %.
Pitch shift: 0 ¢ | Semitones: 0 st | Speed error: 0 %
Key terms
- RPM (revolutions per minute)
- The rotational speed of a turntable platter. Standard formats are 33⅓ RPM (LP), 45 RPM (single), and 78 RPM (shellac).
- Pitch shift (cents)
- The change in perceived pitch caused by a speed difference, expressed in cents. Positive values indicate a higher pitch than intended.
- Wow
- A slow, cyclic variation in turntable speed (below ~6 Hz) that produces a wavering, 'wowing' effect in the audio.
- Flutter
- Rapid, irregular variations in turntable speed (above ~6 Hz) that cause a roughness or 'flutter' in sustained tones.
- Strobe disc
- A calibration tool with printed dot patterns that appear stationary under mains-frequency lighting when the turntable runs at the correct speed, used to verify RPM accuracy.
Frequently asked questions
- Why does turntable speed affect pitch?
- A record encodes audio at a fixed groove density. If it spins faster than intended, frequencies are higher (pitch goes up); slower means pitch drops.