How these tools work, and where the numbers come from.

The timing tools

Delay time, reverb pre-delay and decay, LFO rate, sidechain release, compressor release, BPM-to-milliseconds, tap tempo, and bars-to-minutes all rest on one piece of arithmetic: a quarter note lasts 60,000 ÷ BPM milliseconds. Every other value (note divisions, dotted and triplet figures, bar lengths, Hz for LFOs) derives from that by simple multiplication. There's no proprietary data here and nothing to cite; it's the same math a DAW uses internally to sync effects to tempo. What we add is the conversion done instantly and, where relevant, genre starting points (see below).

The pitch & key tools

Note-to-frequency, pitch shift, sample tuning, transposition, and the scale reference are built on twelve-tone equal temperament (12-TET) with A4 fixed at 440 Hz, the tuning standard used by effectively every modern synth, sampler, and DAW. Each semitone is a frequency ratio of the twelfth root of two (≈1.0595), and twelve of them double the frequency to make an octave. This is long-established, universal music-theory math.

The Camelot wheel uses the Camelot harmonic-mixing system, a DJ-friendly relabelling of the circle of fifths into number-and-letter codes (8A, 8B, and so on) so compatible keys are easy to spot. The scale and chord tools use standard interval formulas: the major scale as whole-whole-half-whole-whole-whole-half, and common progressions written in Roman-numeral harmony that we translate into the chosen key.

References Equal temperament · A440 pitch standard · Circle of fifths

The loudness targets

The LUFS targets come from each streaming platform's own published loudness-normalization specifications, cross-referenced against current mastering-engineer guidance. These figures do change, since platforms adjust them without much announcement, so the tool carries a note to verify against each service's current documentation before a release. LUFS itself follows the ITU-R BS.1770 loudness-measurement standard, which is what your metering plugins implement.

References LUFS / loudness measurement · each platform's artist/creator documentation

The technical tools

Buffer-size-to-latency and audio-file-size are direct engineering calculations. Latency is buffer size ÷ sample rate; uncompressed file size is sample rate × bit depth ÷ 8 × channels × seconds. Both are exact, with no estimation and no lookup, just the arithmetic laid out clearly so you don't have to derive it mid-session.

The streaming royalty estimates

The royalty calculator is the one tool built on figures that are genuinely uncertain. Per-stream payout rates are not officially published as fixed numbers; they vary with listener region, subscription tier, and your distribution deal, and they shift over time. The rates here are widely-reported industry averages, offered for order-of-magnitude perspective only. They should never be treated as a reliable forecast; your distributor's actual reporting is the only real figure.

On the genre presets

Several tools offer genre presets: a techno button on the reverb calculator, a house setting on the sidechain tool, and so on. These are the one place where the numbers reflect convention rather than a formula. They're common starting points for each style, chosen because they tend to work, not laws and not the only correct answer. The underlying math is always exact; the presets just point you at a sensible place to begin so you can then trust your ears. Wherever a preset appears, the tool says plainly that it's a common-practice starting point.

About this project

bpmprodlab is an independent project focused on doing one thing well: fast, accurate studio tools that show their working. The math and specifications come from established music-theory and audio-engineering references; the genre presets reflect widely-used conventions rather than any single "right" answer. Nothing here is padded with filler or gated behind a signup. If you spot a number you'd dispute or a tool that could be sharper, that feedback genuinely shapes what gets built next, so head to the contact page.