Ranking updated
Noise meter apps
A phone microphone can measure noise in decibels well enough for everyday checks. The most rigorous free app is NIOSH Sound Level Meter, built for the US workplace safety institute and lab-tested. Decibel X works on iPhone and Android and shows dBA and dBC. Decibel Meter by ExaMobile is a simple meter with calibration. For a classroom, Too Noisy shows the noise level as a picture children react to. On Apple Watch the built-in Noise app warns you when it is loud.
How we picked: we read each app’s own description and checked the seller in the store. Apps whose seller is in Russia, or that declare no trader, are left out. A phone is not a certified instrument; for legal or workplace measurements use a calibrated meter.
The most accurate free option
NIOSH Sound Level Meter was made for NIOSH, the US institute for workplace safety, so that workers can check whether noise is hazardous. NIOSH says it was tested in a reverberant chamber at its acoustics lab and is accurate within ±2 dBA. It shows LAeq, TWA, maximum and peak levels, noise dose and projected dose with A, C and Z weighting, and it is free with no ads. It is iPhone only.
For iPhone and Android
Decibel X says it is pre-calibrated for Apple devices and measures dBA and dBC with several weighting filters; it can show noise on Apple Watch and export levels to the Health app. It is also on Google Play. Decibel Meter by ExaMobile uses the built-in microphone, shows minimum, average and maximum on a chart and asks you to calibrate before the first use.
Noise meter for a classroom
Too Noisy Starter shows the background noise in a room as a picture, so children see when they get too loud. It is the free starter version; the Pro version adds alarms, awards and themes.
Noise on iPhone and Apple Watch
On Apple Watch Series 4 or later the built-in Noise app measures sound around you and, Apple says, notifies you when the three-minute average passes the threshold you choose. On iPhone the Hearing control in Control Center shows the level of your headphones in decibels; to measure the room, use one of the apps above. For the opposite job, masking noise, see white noise apps.
| App | Best for | Seller | Platforms |
|---|---|---|---|
| NIOSH Sound Level MeterApp Store | accurate checks at work, noise dose | EA LAB for NIOSH | iOS |
| Decibel XApp StoreGoogle Play | dBA and dBC, Apple Watch and Health | SkyPaw | iOS, Android |
| Decibel MeterApp Store | simple meter with calibration | ExaMobile S.A. | iOS |
| Too Noisy StarterApp Store | noise in a classroom | Edtech Monster | iOS |
| Noise on Apple Watch | alerts when it gets loud | Apple, built in | watchOS |
Frequently asked questions
Can a phone measure noise accurately?
Well enough for everyday checks. NIOSH says its iPhone app is accurate within ±2 dBA in lab tests, but for legal or workplace measurements use a calibrated sound level meter.
Is there a noise meter for Android?
Decibel X from SkyPaw is on both the App Store and Google Play.
Which noise meter works for a classroom?
Too Noisy shows classroom noise as a picture children react to; the free Starter version covers the basics.
Does Apple Watch measure noise?
Yes. The Noise app on Apple Watch Series 4 or later measures sound around you and can alert you when it is loud.