Mic test: input level, waveform and local recording
Test your mic in the browser: choose the input, see the dBFS level and waveform, record a clip to play back and read the real settings. Nothing is sent.
Testing your microphone: level in dBFS, format and settings
The test opens your microphone, shows its level in dBFS, draws the waveform and records up to 60 seconds for playback. 0 dBFS is full scale: above it, sound clips. The level is 20 × log10(amplitude), both as RMS and as peak.
Method
The tool asks for the microphone on click, with echo cancellation, noise suppression and automatic gain turned off, so you hear the mic as it is. On each block of 2,048 samples it computes the RMS value (square root of the mean of squares) and the peak (largest absolute value), then converts them to dBFS. The peak bar turns red from 0.99 of full scale, and a message flags a silent mic if nothing goes above −60 dBFS for 3 seconds.
Example
A pure tone with amplitude 0.5 gives a peak of 20 × log10(0.5) = −6.0 dBFS and an RMS level of 20 × log10(0.5 ÷ √2) = −9.0 dBFS.
Recording and settings
Recording uses the first format the browser says it can produce, tested in this order: WebM/Opus, Ogg/Opus, MP4, then WebM; the tool shows the format used. The settings table reads what the browser actually applied: sample rate, channel count and whether processing is on. A missing setting shows as “unknown”.
If the mic is blocked
Browsers only open the microphone on a secure (https) page. After a refusal, allow it again from the icon left of the address. If another app is using the mic, close it. Nothing is sent: the recording stays in browser memory and disappears when you leave the page.
Sources and dates: MDN, getUserMedia(): secure context and errors; MDN, MediaRecorder.isTypeSupported(); MDN, MediaStreamTrack.getSettings() (checked 29/10/2026).
Frequently Asked Questions
How do I test my mic on a PC or phone?
Turn the mic on, allow it, then speak: the meter should rise and the waveform move. Keep the peak below 0 dBFS, since sound clips at 0 dBFS. Record a few seconds and play them back to judge how it sounds.
Why is my mic not working in the browser?
Four causes come up: permission was denied (NotAllowedError), no microphone was found (NotFoundError), another app is using it (NotReadableError) or the page is not on https. The tool shows the cause and what to do.
What format is the recording in?
The browser decides: the tool takes the first format it accepts among WebM/Opus, Ogg/Opus, MP4 and WebM and shows it under the player. Recordings last at most 60 seconds and download in that format.
What does dBFS mean?
dBFS means decibels relative to full scale: 0 dBFS is the most the microphone can pass. Half the amplitude is −6.0 dBFS (20 × log10 0.5). A full-scale pure tone has an RMS level of −3.0 dBFS.
Is this tool really free?
Yes, all tools on Kristools are 100% free and accessible without registration.
Is my data protected?
Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.