Compressor attack and release calculator: release time from BPM

A compressor attack and release calculator turns the song tempo into release times. One beat lasts 60000 ÷ BPM milliseconds, so at 120 BPM a 1/4-note release is 500 ms, a 1/8 is 250 ms and a 1/16 is 125 ms; at 90 BPM the same values are 667, 333 and 167 ms. Pick the source above and the tool pairs that release with a typical attack, ratio and gain-reduction target, for example 15 ms, 1/8 note, 3:1 and 3–5 dB on a lead vocal.

Hearing what attack and release do on a real compressor beats reading about it: here is IvanFromRnD's review of the McDSP APB DC-2 analog compressor.

How to dial it in

1. Enter the song BPM (find it with the BPM Detector if you are not sure).
2. Pick the source and a vibe: transparent, punchy or aggressive.
3. Copy the settings into your compressor, then adjust the threshold until you hit the suggested gain reduction.
4. Match the output (make-up) gain so bypassed and compressed sound equally loud, then judge at the same level.

Release calculator: release time by BPM

Release is how long the compressor keeps reducing gain after the signal drops under the threshold. When it equals a note value at the song tempo, the gain returns on the grid and the movement reads as groove, not pumping. Click any value to copy it.

Rounded to the nearest millisecond. The calculator keeps release between 40 and 800 ms, so at 70 BPM a 1/4 (857 ms) shows as 800 ms; under about 40 ms a release starts tracking low-frequency cycles (a 50 Hz wave repeats every 20 ms), which reads as distortion. Bars and seconds at these tempos: song length calculator. Delay and reverb times: delay and reverb time calculator.

Which note value to pick

1/16 (107 ms at 140 BPM, 125 at 120): rap vocals, kick, snare, drum bus; it resets before the next hit. 1/8 (214 ms at 140, 250 at 120): lead vocal and bass; it rides phrases, not syllables. 1/4 (429 ms at 140, 500 at 120): mix bus, piano, pads, anything where the compressor should be inaudible. Dotted and triplet values suit grooves the straight value fights, such as shuffled hi-hats. A trap beat written at 140 is felt at 70, so its 1/8 (214 ms) is also a felt 1/16; the hip hop key and tempo guide explains why 70 and 140 are the same beat, and how to make effects tempo-synced applies the same math to delays.

Attack and release starting points by source

The values the calculator starts from in its Punchy setting, with release in milliseconds at 120 BPM (a typical pop tempo) and 95 BPM (a typical boom-bap tempo). Gain reduction is what the meter should show on the loud parts, not a threshold. Transparent multiplies attack by 1.6 and takes 1 off the ratio and 1 dB off the target; Aggressive multiplies attack by 0.4 and adds 2 to the ratio and 2 dB to the target.

Starting points for single-band compression; multiband and limiter settings follow different rules.

Reading the table

Drums. The kick's 25 ms attack keeps the click, the snare's 12 ms lets the crack through, the drum bus at 30 ms lets every transient land before the compressor closes; all three release on a 1/16 so the unit has reset before the next hit. Bass and 808. 30 ms keeps the front of the note; a 1/8 release evens sustain without the low end vanishing. Mix bus. 2:1, 30 ms, 1/4 note, 1–2 dB is glue; if the meter wants more, fix the mix. Guitar, piano, pads. Slow attacks and a long release level the performance without flattening it.

Worked example: lead vocal at 95 BPM, rap vocal at 140 BPM

At 95 BPM one beat is 631.6 ms. The lead-vocal preset releases on a 1/8, so 631.6 × 0.5 = 316 ms, with 15 ms attack, 3:1 and a 3–5 dB target. At 140 BPM one beat is 428.6 ms; the rap preset releases on a 1/16, so 428.6 × 0.25 = 107 ms, with 3 ms attack, 6:1 and 5–8 dB. Aggressive on that rap vocal: 1.2 ms, 8:1, 7–10 dB. Transparent on the lead vocal: 24 ms, 2:1, 2–4 dB. A drum bus at 128 BPM gets 117 ms (468.75 × 0.25) with the 30 ms attack unchanged.

Compressor attack and release times for vocals

Vocals get two compressors in series more often than any other source: one compressor doing 6–8 dB sounds squashed, two doing 2–4 dB each sound controlled. The first stage is slow and does the leveling; the second is fast and catches the peaks the first let through. Typical starting points at the song tempo are below; the reasoning is in vocal compressor attack and release and the chain order in serial compression on vocals.

Order is a taste call: slow into fast (the default here) is smoother; fast into slow clamps peaks first so the leveler moves less. Two habits help either chain. Even out the loudest and quietest phrases by 2–3 dB with clip gain before the first compressor (the vocal clip gain planner maps it line by line), and keep the combined reduction near 4–6 dB on a lead, 6–10 dB on an aggressive rap vocal. For more density without more squash, blend a crushed copy on a parallel bus instead of pushing either stage: see parallel compression on vocals.

Why these numbers work

Attack decides how much transient escapes: under ~10 ms clamps peaks (great for rap vocals), 20–30 ms lets drums punch. Release is groove: when it matches a note length — an 8th or 16th at the song tempo — the compressor breathes in time instead of pumping randomly. Ratio sets the attitude, and gain reduction is the real amount of compression: the same 4:1 sounds gentle at 2 dB GR and crushed at 10 dB.

These are starting points that professional engineers actually use — trust your ears for the last 10%. If a compressor has an Auto release, try it too; on program material it often wins.

Compressors worth owning

Aggressive vocals and drums love an 1176-style FET like the Waves CLA-76. Smooth lead vocals sit beautifully in an opto like the Tube-Tech CL 1B. On zero budget, Klanghelm MJUC jr (vari-mu glue) and the Analog Obsession collection are absurdly good for free. Some links are affiliate links — they support the free tools at no extra cost to you. Longer shortlists: best compressor plugins and best free compressor plugins.

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