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Redmoon Converters
🎛️ Music Production

Sidechain Compression Timing Calculator

Sync compressor attack and release to BPM and note divisions for clean sidechain pumping. Includes presets for house, drum & bass and dubstep.

Built and maintained by Paul Clark, Redmoon Software · Checked against what this tool computes on

Attack
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Release
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NoteStraight (ms)Dotted (ms)Triplet (ms)
Quick reference

1 beat (quarter note) = 60 000 / BPM ms. Each note value is a multiple of that beat — 1/16 = ¼ × beat, 1/8 = ½ × beat, etc. For sidechain pumping a common starting point is a fast attack (1/16 to 1/32) and a release that opens up just before the next kick (1/4 to 1/8).

For four-on-the-floor pumping at 128 BPM the kick lands every 468.75 ms. The default 1/4 release is exactly one beat, so the compressor is still recovering as the next kick arrives — that is the classic continuous pump. Pick 1/8 or shorter if you want the level fully back before each hit.

How it works

The tool converts tempo into compressor time constants. One beat — a quarter note — lasts 60000 ÷ BPM milliseconds, so at the default 128 BPM a beat is 468.75 ms. Every note value is a fraction of that: 1/16 is 0.25 × beat, 1/8 is 0.5 ×, 1/1 is 4 ×. The reference table below the readout multiplies each straight value by 1.5 for dotted notes and by 2/3 for triplets, giving all three grids at once.

BPM does the most work, since every figure scales inversely with it. After that come the two note-value selects: attack defaults to 1/16 and offers 1/64 through 1/4, while release defaults to 1/4 and offers 1/16 through 1/1. The genre buttons set both at once. House (124) uses 1/16 and 1/4; Techno (130), D&B (174) and Trap (140) all use 1/32 and 1/8; Dubstep (140) drops the attack to 1/64.

Note values are musical durations, not what your compressor actually does. Plugins define release as the time to recover a set fraction of gain reduction, and curve shape, knee, ratio and lookahead all change the audible envelope — none of which the calculator models. Treat the millisecond figures as a starting point you then dial in by ear. Note too that the built-in tip says release should sit a touch under one beat, yet the default 1/4 release equals a full beat at any tempo.

Frequently asked questions

What attack and release should I use for sidechain pumping at 128 BPM?

With the defaults — 1/16 attack and 1/4 release — 128 BPM gives 117.19 ms attack and 468.75 ms release. The kick lands every 468.75 ms, so shorten the release slightly: pick 1/8, which is 234.38 ms, if the pump feels late.

How do I calculate milliseconds from BPM?

One quarter-note beat is 60000 ÷ BPM milliseconds. Multiply or divide by powers of two for other note values: 1/8 is half a beat, 1/16 a quarter of one, 1/2 twice one. The BPM field accepts anything from 20 to 400 in 0.1 steps.

What are the dotted and triplet columns in the table?

The dotted column multiplies the straight value by 1.5 and the triplet column by 2/3. Dotted timings suit swung or garage-flavoured pumping, triplets suit shuffled and half-time patterns. Both are listed for every note from 1/1 down to 1/64.

Which preset should I use for drum and bass?

The D&B (174) button sets 174 BPM with a 1/32 attack and 1/8 release, which works out at 43.10 ms and 172.41 ms. Techno (130) and Trap (140) use that same note pair at their own tempos, so their millisecond values differ.

Can I use these numbers for a volume-shaper plugin instead of a compressor?

Yes for the timing grid, because the values are just note lengths at your tempo, so the release figure works as an envelope length in a gain-shaping plugin. The calculator has no threshold, ratio or depth control, so shape the curve itself by ear.

Release is the parameter that makes the pump

A sidechain compressor ducks one signal from another, and it is the release — how quickly the gain returns after the trigger — that produces the rhythmic pumping. Set it to a note division and the recovery breathes with the track; set it arbitrarily and it fights the groove.

A release that runs past the next trigger never fully recovers, so the effect becomes a constant gain reduction rather than a rhythm. That is the most common reason sidechaining sounds like a volume drop instead of a pulse.

Attack, and doing it without a compressor

Attack controls how much of the trigger transient survives. A very fast attack ducks the kick's own click along with everything else and can make it disappear; a slightly slower attack lets the transient through before the gain reduction bites, which usually reads as punchier.

Volume-shaper plugins and LFO tools achieve the same result more predictably, because the shape is drawn against the grid rather than emerging from a detector responding to a signal. The trade-off is that they duck on the grid whether or not the trigger played, which a compressor does not.

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