Calcophony

A scientific calculator for composers.

Tempo ratios, tuplet subdivisions, overtone frequencies, metric modulation paths — the kind of things you end up scribbling on manuscript margins or punching into a spreadsheet. Calcophony puts all of it in one place, with exact results you can trust.

Coming soon to the App Store and Google Play

Modules

Tempo Modulation Free

All tempo relationships from a source BPM. Explore all possible tempo modulations from a given starting point in a comprehensive matrix view, with tuplet complexity controls and configurable precision.

Tempo Modulation screen showing a note-value ratio matrix at 120 BPM

Metric Modulation

Plan multi-step modulations between distant tempos. Discover ordered chains of intermediate tempos with pivot note values and cumulative deviation metrics.

Metric Modulation screen showing modulation paths from 120 to 100 BPM

Rhythm & Subdivision

Work out complex rhythmic relationships. Get exact durations, click-track pulses, and equivalent groupings for nested tuplets and polyrhythms.

Rhythm & Subdivision screen showing tuplet durations and groupings

Frequency & Pitch Free

Bidirectional Hz, pitch name, cents, and MIDI conversion. Includes exact cents deviation and customizable reference pitch (e.g., A4 = 440 Hz).

Frequency & Pitch screen showing Hz, note name, cents, and MIDI conversion

Duration Calculator

Convert between tempo, note value, and clock time. Features a batch mode for note value lists and SMPTE-style timecode offsets.

Duration Calculator screen showing note values converted to milliseconds and timecode

Metronome Free

Create metronomes in any time signature with customizable sound sets, accent patterns, gradual tempo changes, and asymmetric meter support.

Metronome screen with customizable click and accent patterns

Polyrhythm Visualizer

Visualize composite rhythms with an interactive circular display. Configure up to 8 independent streams, find coincidence points, and audition the composite pattern with playback controls.

Polyrhythm Visualizer showing a 3:4:5 pattern with circular ring display and coincidence analysis

Harmonic Series

Visualize and audition the overtone series. Compare exact Hz to nearest 12-TET pitch with cents deviation, and play back individual partials.

Harmonic Series screen showing partials from 110 Hz with frequency, pitch, and cents deviation

Interval & Tuning

Compare intervals across tuning systems. See how the same interval differs between 12-TET, just intonation, Pythagorean, meantone, and Werckmeister with exact cents, ratios, and beat frequencies.

Interval & Tuning screen comparing a perfect 5th across 12-TET, just intonation, and Pythagorean tuning

Spectral Calculator

Compute combination tones — sum, difference, Tartini, and second-order products — for any set of input frequencies. Identify which results reinforce existing partials and audition each tone directly.

Spectral Calculator showing combination tones for A4 and E5 with playback controls

Tuner

High-precision chromatic and instrument-aware pitch detection with strobe display. Supports custom tunings, transposing instruments, and reference tone playback.

Tuner screen in strobe mode showing real-time pitch detection for guitar

Under the Hood

True Strobe Simulation

The strobe tuner is a real-time strobe disc simulation rendered by a native GPU module — not a cosmetic overlay on a traditional pitch detection algorithm. The disc rotation responds directly to measured phase, the same way a mechanical strobe tuner does.

Exact Arithmetic

Musical ratios are computed with true fractional arithmetic — no rounding errors, no approximations. Results stay mathematically exact until final display.

All On-Device

Every calculation runs locally. No account, no server round-trips, no telemetry required. Works offline.

Pricing

Free

$0

  • Tempo Modulation
  • Frequency & Pitch
  • Metronome
  • 7-day free trial of all modules

Pro

$9.99 one-time

  • All modules unlocked
  • Future modules included
  • Try free for 7 days
  • No subscription

Schools & institutions: volume pricing is available through Apple School Manager and Google Play for Education. Contact us for details.