Gate Threshold Calculator
Calculate the optimal noise gate threshold in dB by finding a level 30% of the way between your noise floor and your signal level. Use it to set gates that reliably open for wanted signals while silencing background noise between performances.
About this calculator
A noise gate silences a signal when it falls below a set threshold, cutting out background noise, hum, or bleed between phrases. Setting the threshold too high chops off the natural decay of notes; too low and the gate fails to close on noise. This calculator places the threshold at 30% of the dynamic range between noise floor and signal level, using the formula: threshold (dB) = noiseLevel + ((signalLevel − noiseLevel) × 0.3). This means the gate sits just above the noise floor — close enough to reliably close on silence, yet far enough below the signal to open cleanly on transients. The 0.3 (30%) factor is a practical starting point; louder signals with a wide signal-to-noise gap can sometimes use a lower percentage, while noisier sources benefit from slightly higher values.
How to use
Suppose your recording has a noise floor of −60 dB and a signal level of −10 dB. Step 1 – Enter Signal Level = −10 and Noise Level = −60. Step 2 – Calculate the dynamic range: −10 − (−60) = 50 dB. Step 3 – Apply the formula: threshold = −60 + (50 × 0.3) = −60 + 15 = −45 dB. Step 4 – Set your noise gate threshold to −45 dB. This places the gate 15 dB above the noise floor, giving it enough headroom to reliably close on silence while opening cleanly when the signal appears at −10 dB.
Frequently asked questions
How do I set a noise gate threshold to avoid cutting off note decay?
The key is to place the threshold well below the quietest part of the intended signal, including the natural decay tail of notes or the reverb trail after a chord. Start with the calculated value from the formula, then listen carefully to the decay of sustained notes and lower the threshold if the gate is closing too early. Adding a generous release time (50–200 ms depending on the instrument) also helps by keeping the gate open slightly longer after the signal drops below threshold. A gate that sounds slightly sluggish is usually preferable to one that chops off musical content.
What is a good signal-to-noise ratio for a noise gate to work effectively?
A noise gate works best when there is at least 20 dB of separation between the noise floor and the desired signal level. With less than 10–15 dB of separation, the gate threshold ends up dangerously close to the signal level, risking false closures on quieter notes or soft passages. If your signal-to-noise ratio is poor, address the source first — improve gain staging, fix ground loops, or move microphones closer — before relying on a gate. Gates are most effective as the last line of defence against residual noise, not as a substitute for proper gain structure.
Why is the noise gate threshold set at 30% of the dynamic range rather than closer to the noise floor?
Placing the threshold right at the noise floor risks the gate 'chattering' — rapidly opening and closing as the noise level briefly spikes near the threshold. The 30% offset provides a comfortable safety margin above the noise floor so that minor fluctuations in background noise do not accidentally trigger the gate. It also ensures the gate closes smoothly during genuine silences without requiring extremely precise threshold tuning. The 30% value is a practical default; engineers with very clean signals and a wide dynamic range may choose a lower percentage to preserve more of the natural signal decay.