Reverb Decay Calculator
Calculate mathematically synced RT60 decay times in seconds and milliseconds for any tempo. Ensure reverb tails breathe in rhythm with your musical arrangement.
Decay Calculator Widget
Enter your session BPM to calculate musical RT60 decay times in seconds.
| Musical Interval | Duration (ms) | Duration (Seconds) |
|---|
What Is Reverb Decay Time (RT60)?
Reverb decay time—classically defined as RT60—is the time (measured in seconds) required for the sound pressure level in an enclosed space to attenuate by 60 decibels after the sound source abruptly ceases. In music production and DAW plugins, the Decay Time parameter determines how long the diffuse reverberant tail sustains before fading into silence.
When decay times are unsynchronized with song tempo, long reverberant plumes overlap with subsequent chord changes or drum beats, masking bass definitions and making mixes sound washy and indistinct. Synchronizing decay time ensures reverbs breathe naturally with the rhythm.
The Mathematical Decay Formulas
Quarter Note (ms) = 60,000 ÷ BPM
// 2. Common Musical Decay Targets
Half Note Decay (2 Beats) = Quarter Note (ms) × 2 ÷ 1000 // Snare drum standard
1-Bar Decay (4 Beats) = Quarter Note (ms) × 4 ÷ 1000 // Lead vocal / guitar standard
2-Bar Decay (8 Beats) = Quarter Note (ms) × 8 ÷ 1000 // Pad / ambient hall standard
Worked Mathematical Examples Across 5 Tempos
| Tempo (BPM) | Quarter Note (1 Beat) | Half Note (2 Beats) | 1 Bar Decay (4 Beats) | 2 Bar Decay (8 Beats) |
|---|---|---|---|---|
| 80 BPM | 750.00 ms | 1.50 s (1500 ms) | 3.00 s (3000 ms) | 6.00 s (6000 ms) |
| 100 BPM | 600.00 ms | 1.20 s (1200 ms) | 2.40 s (2400 ms) | 4.80 s (4800 ms) |
| 120 BPM | 500.00 ms | 1.00 s (1000 ms) | 2.00 s (2000 ms) | 4.00 s (4000 ms) |
| 140 BPM | 428.57 ms | 0.86 s (857 ms) | 1.71 s (1714 ms) | 3.43 s (3428 ms) |
| 160 BPM | 375.00 ms | 0.75 s (750 ms) | 1.50 s (1500 ms) | 3.00 s (3000 ms) |
Target Decay Envelopes by Instrument
- Snare Drum (0.6–1.2s): Time decay to fade exactly as the next backbeat lands. Read our complete Drum Reverb Guide.
- Lead Vocals (1.4–2.4s): Match decay to 1 musical bar (4 beats) at your tempo. Read our Vocal Reverb Guide.
- Acoustic Guitar & Piano (1.0–1.8s): Keep decay tight to preserve fast fingerpicking articulation.
- Synth Pads & Transitions (2.5–5.0s): Extend decay across 2 or 4 bars to build emotional cinematic tension.
Frequently Asked Questions
Reverb decay time (often expressed as RT60) is the duration in seconds required for the reverberant sound pressure level to drop by 60 dB after the direct sound stops.
Decay is calculated by finding the beat duration (60,000 ÷ BPM) and multiplying it by the number of beats corresponding to musical intervals (e.g., 2 beats for a half note, 4 beats for 1 bar, or 8 beats for 2 bars).
Snare reverb decay should generally not exceed 2 beats (a half note duration, e.g., ~1.00s at 120 BPM) so the tail fades naturally before the next snare backbeat hits.
Muddy decay occurs when reverb tails last longer than chord progressions, causing harmonic dissonance, or when low frequencies below 250 Hz are allowed into the reverb processor. Learn more in our guide on How to Avoid Muddy Reverb.
Related Audio Calculators & Guides
BPM Reverb Calculator
Master tempo-synced calculation engine for pre-delay and RT60 decay.
Pre-Delay Calculator
Calculate fine-tuned pre-delays for 1/64, 1/128, and triplet notes.
BPM Delay Calculator
Sync delay throws, ping-pong echoes, and slapbacks to your tempo.
BPM to Milliseconds
Convert any tempo into standard, dotted, and triplet millisecond values.
How It Works
Complete documentation of all acoustic and musical math formulas.