Reverb Time Delay Calculator

• Speed of sound (air): c ≈ 331.3 + 0.606·T (m/s, T in °C).
• Distance delay: t = d / c, then ms = 1000·t.
• First reflection delay: t ≈ (2·d_wall)/c.
• Milliseconds per beat: ms_beat = 60000 / BPM.
• Tempo delay: ms_delay = ms_beat · beats (beats from the chosen division).
• Samples: samples = (ms_delay/1000) · sample_rate.
• RT60 (Sabine): RT60 ≈ 0.161·V/A, where V is room volume and A is equivalent absorption area.

1. Pick units, then choose speed mode for your environment.
2. Enter BPM and a note division for tempo-synced delay time.
3. Enter distance for a physical delay estimate in milliseconds.
4. Enter source-to-wall distance to estimate first reflection timing.
5. Optionally enter room size and absorption to estimate RT60.
6. Press Calculate to view results above this form.
7. Use CSV or PDF buttons to export the result summary.

Reverb Time Delay Guide

1) Why timing matters in reverb

Reverb is not only a “size” control; it is a timing system that shapes depth and clarity. Early reflections arrive first, then the decay tail fills the gaps. Small changes—like 10 ms of pre-delay—can move a vocal forward without raising volume. Use this calculator to compare physical delays (distance) and musical delays (tempo) in one place.

2) Understanding pre-delay and reflections

Pre-delay is the gap between the dry sound and the first strong reflection of the reverb. A common starting range is 10–30 ms for lead vocals and 0–15 ms for tighter drums, depending on arrangement density. The “first reflection” estimate here uses an out-and-back path (2 × wall distance) divided by the speed of sound.

3) Tempo-synced delays for rhythmic space

Tempo timing keeps repeats out of the way of the groove. The core relationship is 60,000/BPM = milliseconds per beat. At 120 BPM, one beat is 500 ms, an eighth note is 250 ms, and a dotted eighth is 375 ms. Use dotted and triplet options when you want movement without stepping on straight quarter-note pulses.

4) Distance-based delay and the speed of sound

Physical delay is useful for slapback, room mics, and aligning reflections. At about 20°C, sound travels roughly 343 m/s, which is about 2.92 ms per meter. That means a 3 m path is near 8.75 ms. If your space is warmer, the speed increases slightly, so the delay decreases a bit—this calculator adjusts that automatically in temperature mode.

5) Choosing note divisions and groove

A quarter-note delay emphasizes the pulse, while eighth notes add energy and motion. Dotted values (×1.5) often create the classic “bounce,” and triplets can soften rigid patterns. Try matching a delay to the song’s subdivision, then nudge by 5–20 ms if the vocal consonants feel masked or if the snare loses impact.

6) Sample rate and buffer-friendly values

Many plugins display delay in samples, not milliseconds. Converting is simple: samples = (ms/1000) × sample rate. At 48,000 Hz, 1 ms equals 48 samples; at 44,100 Hz, 1 ms equals 44.1 samples. If automation clicks, try rounding to whole samples or slightly adjusting the delay time.

7) Estimating RT60 with room data

RT60 is the time for sound to decay by 60 dB. The optional estimate uses a Sabine-style model: RT60 ≈ 0.161 × V/A, where V is room volume and A is absorption area. Lower average absorption (for example 0.15) tends to increase decay time; more treatment (for example 0.40) reduces it.

8) Practical workflow for mixing decisions

Start by choosing a tempo division that supports the song, then set pre-delay from the first reflection estimate or a vocal-friendly range. Check the distance delay for realistic slapback. Finally, compare the RT60 estimate to your target vibe: short for tight pop, longer for cinematic FAQs. Export CSV/PDF to document settings across revisions and sessions.

FAQs

1) What is a good starting pre-delay for vocals?

Many mixes start around 10–30 ms to keep the vocal upfront while still sounding spacious. If consonants smear, increase pre-delay slightly. If the vocal feels detached, reduce it.

2) Should I use tempo delay or distance delay?

Tempo delay is best when repeats must lock to the groove. Distance delay is useful for realism (slapback, reflections, room-mic alignment). It is common to combine both: tempo for repeats, distance for early reflection timing.

3) Why do dotted and triplet values sound “more musical” sometimes?

Dotted and triplet divisions avoid stacking repeats directly on straight beats. That creates motion and reduces masking, especially in busy arrangements, without needing excessive feedback or high mix levels.

4) What does the first reflection value represent?

It estimates the earliest strong bounce from a nearby surface using an out-and-back path: roughly 2 × wall distance divided by sound speed. Use it as a starting pre-delay reference, not a strict measurement.

5) How does temperature affect delay calculations?

Warmer air slightly increases the speed of sound, which reduces the computed delay for the same distance. Cooler air does the opposite. The effect is small but noticeable when aligning tight reflections and slapback.

6) What average absorption should I enter for RT60?

Use a rough broadband guess: 0.10–0.20 for reflective rooms, 0.25–0.35 for lightly treated spaces, and 0.35–0.50 for heavier treatment. This is an estimate; real absorption varies by frequency.

7) Why convert milliseconds to samples?

Some workflows require sample-accurate values, especially when automating or matching delays across sessions. Samples also help avoid rounding differences between plugins and DAWs. This calculator shows both milliseconds and sample counts for quick transfer.