BPM to Delay & Reverb Time Calculator — ms, Hz & Frequency

A professional timing reference that answers one question: what does this time value actually mean — musically, acoustically and in DSP terms? Type a tempo (or pick 128), and the calculator above turns it into a full grid of straight, dotted and triplet values in milliseconds. Then it reads any millisecond you give it — down to 0.01 ms — as an Hz equivalent, as waveform cycles, as phase rotation at your chosen frequency, and as samples at your sample rate. All math runs locally in your browser: the number never leaves this page.

What is a BPM to Delay Calculator?

A delay plugin wants milliseconds. Your song has a tempo. A BPM-to-delay calculator is the translation layer between those two worlds: it converts "one eighth note" into the exact millisecond value you should type into the plugin so the echo lands on the grid. This tool does that conversion and then goes further than a simple converter — it treats the resulting time as a physical quantity you can interrogate: how many waveform cycles fit inside it, what phase rotation it causes at a given frequency, where its comb-filtering notches sit, and how long it is relative to a bar in your meter.

If you have ever typed a delay time from memory ("around 120 ms?") and heard it sit slightly off the groove, this is the tool that removes the guesswork. If you need to detect the tempo of an existing file instead, use our free BPM & key analyzer first — then bring that number here.

How BPM Converts to Milliseconds

The master formula: quarter note = 60 000 / BPM. At 120 BPM a quarter note is exactly 500 ms; at 128 BPM it is 468.75 ms; at 90 BPM it is 666.67 ms. Everything else in the calculator derives from that one number:

Dotted values multiply a straight value by 1.5; triplet values by 2/3 — both are exact, so the calculator keeps full internal precision and only formats for display (you will never see 166.667 ms rounded into something it is not).

BPM, beat duration and meter are three different things, and this calculator treats them that way: BPM counts beats per minute; a bar's length depends on your time signature; note subdivisions (1/8, 1/16…) are fractions of the beat. Pick 3/4 and the "1 bar" row shortens to three beats while every note division stays untouched — changing the meter never changes what a quarter note is at your tempo.

Delay vs Reverb Pre-delay

Delay and reverb pre-delay solve different problems, even though both are just "a few milliseconds":

• Delay repeats the signal. Musical delay times ride the beat grid — 1/8, dotted 1/8 (the classic "swing" echo), triplets, or a fixed ~100 ms slapback for that guitar echo. The calculator's delay presets resolve against your tempo, so the same preset gives different millisecond values at 90 BPM and 150 BPM — which is exactly what you want.
• Reverb pre-delay pushes the first reflections away from the source without smearing it: typically a few milliseconds up to ~90 ms, keeping transients tight while the tail still opens up space. The presets in the tool are starting points in that territory.

Treat every preset as a starting point, not a rule — dial by ear against the actual track. What the calculator gives you is an exact, tempo-locked number instead of an estimate.

Very Short Delay Times (0–50 ms)

Below ~50 ms, listeners stop hearing "echo" and start hearing space or phase movement. This range behaves very differently from musical delays, which is why the tool has a dedicated ultra-short section with sub-millisecond precision:

• 0.01–1 ms — shorter than one cycle of most bass frequencies. At this length the effect shifts phase (and, inside filters, spectral content); it cannot act as a rhythmic delay at all.
• 1–30 ms — pre-delay and early-reflection territory: width and space added to the source, no discrete repeat heard.
• 30–50 ms — the edge of both worlds; for narrow-bass content this is also where dry/wet interference becomes most audible (see comb filtering below).

The custom-time input accepts 0 as a valid delay (a zero-offset wet signal simply aligns with the dry one), shows "N/A" instead of Infinity wherever a division by that zero would occur, and keeps small values honest — 0.05 ms is displayed as 0.05 ms, never rounded to 0.

How Frequency Relates to Delay Time

Time and frequency are the same quantity viewed from two sides: period = 1000 / Hz and Hz equivalent = 1000 / ms. A delay of 10 ms is a "2 Hz" event if it repeats; one cycle of 100 Hz lasts exactly 10 ms. The cycles relationship follows directly — cycles = (time ÷ 1000) × frequency:

• 10 ms contains 1 cycle at 100 Hz, 10 cycles at 1 kHz and 100 cycles at 10 kHz.
• That is why the same 5–15 ms region that is "a bit of space" for a snare (≈200–400 Hz fundamental) already spans several full bass-note cycles — the number only means something once you say at what frequency.

This matters most in multiband work, mastering and compressor attack/release analysis: a detector time measured against one band says nothing about another. The calculator's frequency-range input (e.g. 80–120 Hz) evaluates your selected time at the start, middle and end of that band so you can see the spread instead of assuming one number represents it all.

Phase Shift and Comb Filtering

A delay of d ms rotates a sine wave by phase = d × f × 0.36° (d in ms, f in Hz). The tool always prints phase together with its frequency — "5 ms = 180° at 100 Hz" is the honest form; bare "5 ms = 180°" would be a category error, because at 1 kHz that same delay rotates a full turn and back (360°, inaudible). When total rotation exceeds one turn the display also shows it (e.g. 1800°), with the normalized 0–359.99° value as the primary figure.

Comb filtering is what that phase does to a real spectrum when you sum dry + delayed signal: where the delay spans an odd half-integer number of cycles, the two waves cancel; where it spans whole cycles, they reinforce. For d = 5 ms the ideal two-path math puts cancellations at (2k+1)·(1/2d) — 100, 300, 500, 700 Hz — and reinforcements at k/d — 200, 400, 600 Hz. The calculator lists the first terms inside 20 Hz–20 kHz and draws them on a logarithmic scale with your selected frequency labeled.

Read this section as a reference for an ideal two-path system, not a prediction of your plugin: real response also depends on dry/wet ratio, polarity, feedback amount, internal filtering, stereo routing and overall architecture. It is a map of where interference risk lives — so you can check whether your narrowest bass content happens to sit under a notch.

Attack and Release Timing for Compression

The Compressor/Limiter section analyzes attack, release, lookahead and hold as context, because one rule here is absolute: BPM, frequency and key cannot determine the "correct" setting of any of them. Dynamics are shaped by your detector, gain structure and plugin architecture — no tempo or pitch value can predict that from outside.

What the section does give you, for each parameter: the exact milliseconds (and seconds), samples at your chosen sample rate (1 ms = 48 samples at 48 kHz), its relationship to your musical grid ("X% of one beat at 128 BPM"), and — against a context band you pick (Sub, Bass, Low Mid, Mid, High Mid, High or custom) — how many cycles it spans and what phase rotation that implies at the band edges. So "attack = 10 ms, band 50–200 Hz" reads as: 0.25 cycle at 50 Hz, 2 cycles at 200 Hz. That is a fact you can decide with; it is not a recommendation being dressed up as one.

Using Frequency as a Timing Reference

The six band presets (Sub 20–60 Hz … High 5–20 kHz) exist so timing values get checked against ranges, because any single frequency inside a band is just one point of view. Attack and release rows show both edge frequencies plus the implied cycles, so "is this attack fast enough for my kick?" becomes something you can see in numbers — and then finish with your ears. Frequency is context here: it frames what a timing value means physically; it never overrides the musical grid or invents dynamics settings on its own.

Key Frequency Reference

Pick a root, mode and tuning (432/440/442 Hz or custom A4) and the tool lists the seven notes of that scale at the chosen octave with their equal-temperament frequencies — plus optional harmonics 1–12 of the root (bounded; it stops listing above ~24 kHz). With your attack time set, each note also shows how many cycles fall inside it.

Two honesty notes on what this block is not: it is a reference, not an analysis of your audio — a real signal contains harmonics, transients and noise far beyond the scale's fundamentals. And it does not automatically assign compressor settings; "A minor" changes nothing about which attack suits your bass drum. It exists so that when you think in note terms ("the A1 at 55 Hz"), you can immediately see what 10 ms means for it: 0.55 cycles. If you want the other side of the key story — how these same keys line up for harmonic mixing between tracks — our harmonic mixing & Camelot wheel guide covers that.

BPM to Hz Conversion (and back)

Every timing row carries its Hz equivalent — the repetition rate of an event with that period (quarter at 120 BPM = 2 Hz). The reverse calculator does the inverse with the exact formula: give it a time and a grid line ("375 ms as a dotted 1/8"), and it reports the tempo where that equality holds — 120 BPM, to full precision. If you keep a habit of "that delay felt like an eighth at around 120," this turns the habit into arithmetic: any millisecond value can be pinned to the exact tempo and subdivision it belongs to, which is how you reproduce a feel across sessions without re-measuring by ear every time.

Your numbers stay on your device

Every figure on this page — tempo grid, cycles, phase, comb frequencies, sample counts, key notes — is computed locally in your browser by a pure calculation module with unit tests behind it. There are no backend requests for calculations, no upload and no account: you can type any number and share the exact same state as a URL (?bpm=128&ms=375). For loudness-side work on an actual file, pair this with our free LUFS & true-peak normalizer; for full tonal shaping there is the AI mastering service (3 free tracks a day).

Frequently Asked Questions

How do I convert BPM to milliseconds?

Divide 60 000 by your BPM. At 128 BPM that gives 468.75 ms per quarter note; halve it for an eighth, multiply by 1.5 for a dotted value, and so on. The calculator does the whole grid at once — straight, dotted and triplet for each division from one bar down to 1/256.

What is 120 BPM in milliseconds?

The quarter note (the beat) is exactly 500 ms at 120 BPM. From there: eighth = 250 ms, sixteenth = 125 ms, dotted eighth = 375 ms, eighth triplet ≈ 166.667 ms, bar in 4/4 = 2 000 ms.

What is the delay time for a 1/8 note?

One eighth of your beat: at 120 BPM that is 250 ms; at 128 BPM about 234.375 ms. Tap the "1/8" preset in the calculator and it resolves against whatever tempo you have set — a musical delay should always be re-derived when the tempo changes, not kept as a fixed number from another song.

What is a dotted 1/8 delay?

A straight eighth multiplied by 1.5 (it adds half its own length): 375 ms at 120 BPM. It lands between grid positions and is the classic "swinging" echo time — often the first thing to try when a plain eighth feels too rigid against a groove.

What is a triplet delay?

An eighth note × 2/3 (three of it in the space of two straight eighths): about 166.667 ms at 120 BPM. Triplet delays sit closer to the beat than straight eighths and read as busier, syncopated repeats — useful when a regular eighth starts sounding too much like a clock.

What happens with a 5 ms delay?

You are in pre-delay / early-reflection territory: no audible echo at that length for most material, but real consequences elsewhere — roughly one full cycle of phase rotation at 100 Hz (360°), two cycles at 200 Hz, and ideal dry+wet summing notches near 100/300/500 Hz. The tool's comb section shows the full reference list; remember a real plugin's response also depends on mix ratio, polarity, feedback and routing.

How does frequency affect delay?

It changes what the same millisecond means. A fixed delay spans more waveform cycles at higher frequencies, so its phase rotation (and any interference with the dry signal) scales linearly with frequency: 5 ms is a half-cycle at 100 Hz but five full cycles at 1 kHz. That is why the calculator reports cycles and phase at your chosen reference frequency — and across a whole band when you set one.

What is phase shift?

The rotation a time offset applies to a wave, in degrees: delay × frequency × 0.36° per millisecond-hertz pair (equivalently, full rotations = delay-seconds × frequency). Half of a cycle (180°) cancels strongest; whole cycles (360°, 720°…) arrive back "in phase." The calculator always states it with its frequency — "5 ms = 180° at 100 Hz" — because the degrees alone are meaningless without saying which wave rotated.

What are comb-filtering frequencies?

The periodic notches and peaks that appear when you sum a signal with a delayed copy of itself: cancellations where the delay covers an odd half-integer number of cycles, reinforcements at whole-cycle counts. For a 5 ms offset the first terms fall near 100, 300, 500 Hz (notches) and 200, 400, 600 Hz (peaks). These are reference values for an ideal two-path system — real plugins move them around with dry/wet ratio, polarity, feedback and internal filtering.

Can BPM determine compressor release?

No tempo number can determine it — release is a property of your detector and envelope against the dynamics of this specific track, which no external value predicts. What BPM gives you is context: "release = 500 ms is one beat at 120 BPM" tells you how long that tail feels relative to the grid. Use the relationship as information for an ear-led decision, not as a setting generator.

Does frequency determine compressor attack?

Not by itself. A band only tells you what a given attack time spans in waveform terms — "5 ms = 0.25 cycle at 50 Hz but 1 full cycle at 200 Hz" is a fact, not a prescription like "100 Hz requires 10 ms." The calculator presents that relationship as context next to your chosen band; the setting itself stays a musical/auditory decision made by you.

How can track key be used as a frequency reference?

As exactly that — a reference. Choose, say, A minor and the tool lists the scale's note frequencies (A = 55/110/220 Hz across octaves at standard tuning), so when you think "the root around 55–110 Hz" you can immediately see what your attack time covers in cycles. It is pitch-class context for reasoning about low-end timing, not a claim about the frequencies actually present in your file (harmonics, transients and noise always are), and it never assigns compressor settings on its own.