Vinyl RPM Pitch Calculator
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What Your Result Means
- Speed Change: Percentage increase or decrease in playback speed (positive = faster, negative = slower)
- Pitch Shift (Semitones): Change in musical pitch measured in semitones (12 semitones = one octave)
- Pitch Shift (Cents): Finer pitch measurement where 100 cents = 1 semitone (more precise for small adjustments)
- Duration Ratio: How long the track takes relative to original (e.g., 0.74× means it plays in 74% of original time)
How This Calculator Works
The speed ratio (playback RPM ÷ original RPM) determines all other values. Pitch and speed are linked logarithmically: the ratio of frequencies determines the pitch shift in semitones using the formula semitones = 12 × log₂(speedRatio). When you play a record at a different speed, both pitch and duration change proportionally. A doubling of speed raises pitch by 12 semitones (one octave) and halves the duration. This is essential for DJ mixing and understanding phonograph playback.
Quick Questions
What happens if I play a 33 at 45?
The record plays 35% faster, raising the pitch by about 7 semitones (between a perfect 5th and octave). The duration shrinks to 73% of original length. It will sound noticeably higher and faster.
What are cents in music?
A cent is 1/100th of a semitone, used for precise pitch measurements. Equal temperament defines 1200 cents per octave. Used in tuning and pitch-shifting specifications.
Why is pitch shift logarithmic?
Human hearing perceives pitch logarithmically. A doubling of frequency sounds like the same interval regardless of the starting pitch. This is why musical intervals are based on frequency ratios, not differences.
Can I use this for DJ mixing?
Absolutely. DJs use pitch control to match the pitch and tempo of two records. Understanding semitones and cents helps synchronize tracks musically rather than just tempo-matching.
What RPM were 78s actually recorded at?
78 RPM was the standard for shellac records in the early 20th century. It allowed better fidelity than slower speeds but limited playing time to about 3–4 minutes per side.
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Method & review
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.