Audio calculators

Reverb Calculator

Updated Aug 29, 2026 By Jehan Wadia
Rate Formulas
Tempo & Display Settings
Valid range: 20–300 BPM. Results update as you type.
All table and chart values convert to this unit.
Drives the highlighted cards and step-by-step panel.
Tap Tempo
Taps: 0 — Detected BPM: —
Tap at least 3 times. Pausing for 3 seconds starts a new set.
Common Tempo Presets
Selecting a preset fills the BPM field and recalculates instantly.
Beat (1/4 Note)
500.00 ms
at 120 BPM
1 Bar (4/4)
2000.00 ms
4 beats
Pre-Delay — Hall
62.50 ms
1/32 Note
Total Reverb — Hall
4000.00 ms
2 Bars (8 beats)
Reverb Time by Room Size
BPM-synced pre-delay, decay and total reverb times for four room-size presets at 120 BPM.
Room Size Pre-Delay (ms) Decay Time (ms) Total Reverb (ms)
Pre-Delay vs. Decay by Room Size
Note Subdivision Timing Reference
Duration of each note subdivision at 120 BPM, with the reverb window that follows it.
Note Value Label Note Value Pre-Delay (ms) Suggested Decay (ms)
Step-by-Step Solution

Introduction

Reverb sounds best when it fits the beat of your song. This Reverb Calculator turns your tempo (BPM) into exact reverb times in milliseconds or seconds. Type in your BPM, or tap the button in time with your track, and the calculator does the math for you. If you only need the raw beat and delay timings, our BPM Calculator covers that side of the workflow.

It gives you three key numbers: pre-delay (the short gap before the reverb starts), decay (how long the tail rings out), and total reverb time. You get values for four room sizes — Hall, Large Room, Small Room, and Tight Ambience — plus a full note timing chart from whole notes down to 64th notes.

When your reverb tail ends on the beat, your mix stays clean and your drums stay punchy. Reverb that is too long muddies the low end and blurs the rhythm. Use these BPM-synced settings in any DAW or reverb plugin to keep your space big without losing clarity.

How to use our Reverb Calculator

Enter your song's tempo and pick a room size. The calculator shows the pre-delay, decay time, and total reverb time that match your beat, plus a chart, a note timing table, and the math behind it.

Tempo (BPM): Type the beats per minute of your track. Use any number from 20 to 300. The results change as you type.

Show times in: Choose milliseconds (ms) or seconds (s). Most reverb plugins use milliseconds. If you need to move between decimal values and clock time elsewhere in your session notes, the Time Converter Calculator can help.

Worked example room: Pick the room size you want: Hall, Large Room, Small Room, or Tight Ambience. This choice sets the highlighted cards and the step-by-step answer.

Tap to the Beat: Don't know your BPM? Tap the button in time with the music at least 3 times. The tool finds the tempo and fills it in for you.

Reset Taps: Clears your taps so you can start a new count.

Common Tempo Presets: Click Largo, Andante, Moderato, Allegro, or Presto to load that tempo fast.

Calculate: Click this to run the numbers again with your current settings.

Reset: Click this to go back to the default 120 BPM setup.

What Is BPM-Synced Reverb?

Reverb is the sound that keeps ringing in a room after a note stops. It is made of thousands of tiny echoes bouncing off walls, floors and ceilings. In a mix, reverb adds space and depth. But if the reverb time does not match the song's tempo, the tail smears the beat and the track sounds muddy.

BPM-synced reverb fixes that. You set the reverb times to match note lengths in your song, so the tail fades out right as the next beat or bar lands. The math starts with one simple step: find how long one beat lasts.

The Core Formula

One beat (a quarter note) in milliseconds is:

60,000 ÷ BPM = beat length in ms

At 120 BPM, that is 60,000 ÷ 120 = 500 ms per beat. One bar in 4/4 time is four beats, or 2,000 ms. Every other note value comes from cutting or doubling that number. It is a straight division problem, and the note values are just simple fractions of that beat length.

Pre-Delay and Decay

Pre-Delay

Pre-delay is the short gap between the dry sound and the start of the reverb. It copies the time it takes for sound to hit a wall and come back. Short pre-delay (5–20 ms) sounds like a small, close room. Longer pre-delay (30–100 ms) keeps vocals and drums clear because the tail starts after the attack, not on top of it. Because sound travels about 343 m/s in air, pre-delay is really a distance measurement — the Speed Distance Time Calculator shows how far a reflection travels in any given number of milliseconds.

Decay Time

Decay is how long the tail takes to fade away. Engineers often call this RT60 — the time it takes the sound to drop by 60 decibels. Big halls have long decays. Small rooms have short ones. If you want to work with those level drops directly, the dB Calculator handles decibel math, and the Wavelength Calculator helps you match room dimensions to the frequencies that build up in them.

Pre-delay plus decay equals the total reverb time. This tool splits that total for you.

Typical Room Sizes

  • Hall — about 2 bars of total reverb. Big, wide and dramatic. Good for pads, strings and ballad vocals.
  • Large Room — about 1 bar. Roomy but still tight enough for a full mix.
  • Small Room — a half note. Adds glue without washing out the track.
  • Tight Ambience — a quarter note. Just enough space to stop a dry track from sounding flat. Great for fast drums and rap vocals.

Real rooms behave the way they do because of their size and surfaces. If you are treating or building a studio space, run the dimensions through the Volume Calculator and the Square Footage Calculator to work out how much absorption you need, and the Insulation Calculator for wall and ceiling material estimates.

Why Tempo Matters

Faster songs need shorter reverb. At 176 BPM a beat is only about 341 ms, so a two-bar hall tail runs over three notes and blurs everything. At 60 BPM a beat is a full second, so long tails have room to breathe. That is why the same reverb preset can sound great on one song and terrible on another.

Tempo also drives track length. If you need to know how many seconds a given number of bars fills, the Seconds Calculator and Minutes Calculator make quick work of arrangement planning.

Quick Tips

  • Start with a note value one step shorter than you think you need. It is easy to add more.
  • Use longer pre-delay to keep lead vocals up front and clear.
  • Cut low frequencies from the reverb send below about 200 Hz to stop mud. The Frequency Calculator helps you find the notes those low tones sit on.
  • Check your reverb in mono. If it disappears or sounds boxy, shorten the decay.
  • Watch your session file sizes when you print long reverb tails — the Data Transfer Calculator is handy before sending stems to a collaborator.
  • Trust your ears last. These numbers are a starting point, not a rule.

Related Audio and Studio Tools

Formulas used

Beat (quarter-note) length from tempo
t_{beat} = \frac{60000}{\text{BPM}}
Bar length (4/4)
t_{bar} = 4 \times t_{beat}
Total reverb time for a room preset
t_{total} = t_{beat} \times m_{total}
Pre-delay from note subdivision
t_{pre} = t_{beat} \times m_{pre}
Decay tail
t_{decay} = t_{total} - t_{pre}
Suggested decay for a note subdivision
t_{decay} = t_{beat} \times (m_{next} - m_{note})
Detected BPM from tap tempo
\text{BPM} = \frac{60000}{\frac{1}{n-1}\sum_{i=2}^{n}(t_i - t_{i-1})}
Unit conversion (milliseconds to seconds)
t_{s} = \frac{t_{ms}}{1000}

Frequently asked questions

What is the difference between total reverb time and decay time?

Total reverb time is pre-delay plus decay. Decay is only the tail.

Most plugins ask for these as two separate knobs. Put the Pre-Delay number in the pre-delay box and the Decay Time number in the decay or RT60 box. Do not enter the total.

Why is the Hall pre-delay shorter than the Large Room pre-delay?

Each room preset is locked to one note value. Hall uses a 1/32 note. Large Room uses a 1/16 note.

A hall tail is already very long, so a short gap keeps it from swallowing the next beat. If you want a longer gap, just pick any value you like from the Note Subdivision table.

What does the Suggested Decay column mean in the note table?

It is the time between that note and the next longer note.

So if you use a 1/16 note pre-delay, the suggested decay makes the whole reverb end right on the 1/8 note. Your tail lands on a musical spot instead of a random one.

Does this work for songs in 3/4 or 6/8 time?

Yes. Beat length never changes, so all the note values still work.

Only the bar length is different. In 3/4, one bar is 3 beats, not 4. Take the beat number from the top card and multiply it by 3 (or by 6 for 6/8).

How do I get dotted or triplet reverb times?

Take any time from the table and do simple math:

  • Dotted: multiply by 1.5
  • Triplet: multiply by 0.667

At 120 BPM, a 1/8 note is 250 ms. Dotted 1/8 is 375 ms. Triplet 1/8 is about 167 ms.

How many times do I need to tap the beat?

Three taps is the minimum. Six to eight taps gives a much steadier number.

If you stop for 3 seconds, the tool clears your taps and starts a fresh count. You can also hit Reset Taps at any time.

Should I use milliseconds or seconds?

Use milliseconds for pre-delay. Almost every plugin uses ms there.

Use seconds for decay if your reverb shows decay in seconds, which many do. You can flip between the two at any time with the dropdown.

Which room size should I pick for my track?

  • Lead vocals: Large Room or Hall on a send
  • Snare and drums: Small Room or Tight Ambience
  • Rap vocals: Tight Ambience
  • Pads and strings: Hall
  • Acoustic guitar: Small Room

Fast songs need smaller rooms. Slow songs can handle bigger ones.

Is this the same as an RT60 room calculator?

No. This tool matches reverb to your song's tempo. It is for mixing.

A real RT60 calculator uses room size and wall materials to find how long a real space rings. That is for acoustic treatment work, not for setting a plugin.

Can I use these numbers for delay as well?

Yes. The Note Subdivision table gives the exact length of every note value at your tempo.

Those same numbers work for delay, tremolo rate, gate timing, and sidechain release.

My reverb still sounds muddy. What should I fix first?

Try these in order:

  1. Shorten the decay by one note value.
  2. Add more pre-delay so the tail starts after the attack.
  3. Lower the wet level on the send.
  4. Cut some 250–500 Hz out of the reverb return.

My plugin has a tempo sync button. Do I still need this?

Usually yes. Most reverb plugins only sync the pre-delay or the modulation rate, not the decay tail.

Typing the exact decay number gives you control over the part that matters most.

Why is the BPM limited to 20 to 300?

That range covers nearly all real music, from very slow ballads to fast drum and bass.

If your track is faster than 300, enter half the tempo and use the doubled note values instead.

What if my song changes tempo?

Run the calculator again for each tempo. Then automate the decay and pre-delay in your DAW at the change point.

If the change is small, one setting from the main tempo is usually fine.

Can good reverb settings fix a bad-sounding recording room?

No. Room sound baked into a recording stays there. Reverb adds space, it does not remove it.

Fix the room first with absorption panels at the first reflection points and bass traps in the corners. Soundproofing keeps noise out. Acoustic treatment shapes the sound inside.

Should the reverb tail end exactly on the beat?

Aim for it to end just before the next beat or bar. That leaves a tiny bit of clean space so the next hit sounds punchy.

The values here already do this, since the tail fades out instead of stopping hard.

Do I have to click Calculate every time?

No. Results update as you type or change any setting.

The Calculate button is there if you want to run the numbers again, and Reset takes you back to 120 BPM.

Can I use this for live sound?

Yes. Find the band's tempo with the tap button, then set the reverb unit on your desk to match.

For live rooms, stay near the Small Room or Tight Ambience values. Big spaces already have plenty of natural reverb.