Phone & browser
How to measure decibels on your phone
You can check noise levels with the phone in your pocket. Here are the options for iPhone, Android and the browser, how accurate they are, and how to calibrate for better readings.
Option 1: in your browser (any phone or laptop)
The quickest way is a web decibel meter: no install, works on iPhone, Android, Mac, Windows and Chromebook. The browser uses the Web Audio API to read the microphone level and turn it into an approximate dB number. Audio stays on your device.
Option 2: on iPhone
If you have an Apple Watch, its Noise app measures environmental sound, and iOS can show headphone audio levels from Control Center via the Hearing control. For room noise on the phone itself, use a browser meter like LoudCheck or a dedicated sound meter app. iPhone microphones are fairly consistent between models, which makes a single calibration offset more useful.
Option 3: on Android
Most Android phones have no built-in sound meter, so use a browser meter or an app from Google Play. Android hardware varies widely, so calibrating against a reference matters even more than on iPhone.
How accurate is a phone decibel meter?
Phone mics are designed for speech, not measurement. Common limits:
- Unknown sensitivity: browsers don’t reveal mic sensitivity, so an offset is assumed (LoudCheck adds +94 dB to the digital level). Uncalibrated readings can be off by 5–10 dB or more.
- Processing: echo cancellation, noise suppression and auto-gain can change the level. LoudCheck asks the browser to turn them off, but some devices (especially iOS Safari) may still apply processing.
- Range: very quiet rooms read too high because of mic self-noise; very loud sounds above about 100–110 dB may read low because the mic or converter compresses or clips.
- Frequency response: small mics roll off deep bass, and our reading is unweighted rather than dBA.
How to calibrate a phone decibel meter
- Open the meter over HTTPS. Open LoudCheck in Safari on iPhone or Chrome on Android. Microphone access only works on secure https pages.
- Tap Start and allow the microphone. Choose Allow when the browser asks. If you blocked it, re-enable Microphone for the site in browser settings.
- Find a reference. Put a certified sound level meter or a known calibrated app next to your phone, pointing both at the same steady sound such as a fan, pink noise or music.
- Adjust the calibration offset. Move the calibration slider until LoudCheck shows the same steady reading as the reference. The offset is saved on that device and browser.
- Measure consistently. Keep the mic uncovered, hold the phone at the same distance, avoid wind and handling noise, and let the reading settle for 30 seconds.
Next: see what 60, 80 and 100 dB sound like, or check safe exposure times.
Frequently asked questions
Can I measure decibels on my iPhone without an app?
Yes. Open an online decibel meter such as LoudCheck in Safari, tap Start and allow the microphone. It gives an approximate dB reading without installing anything.
How accurate are phone decibel meters?
Uncalibrated, they are usually within several dB for moderate everyday sounds and can be off by 10 dB or more at very low or very high levels. Calibrating against a known reference improves consistency, but a phone is still not a certified meter.
Why does my phone show a different dB than another app?
Each app or website assumes a different microphone sensitivity and may use different weighting (dB vs dBA) and time response. Calibrate both against the same reference to compare them fairly.
Why is the microphone not working in my browser?
Microphone access needs an https page, a tap on Start, and permission for the site. In-app browsers inside social or chat apps often block the mic, so open the page in Safari or Chrome.
Does a browser decibel meter record my audio?
LoudCheck does not. It only reads the signal level in real time in your browser; no audio is saved or sent to a server.