Online Decibel Meter — Use Your Phone as a Sound Level Meter
No app needed · free in your browser

1. Tap "Allow microphone and start".
2. Choose "Allow" when your browser asks for microphone access.
3. The gauge and the number start moving and show the noise level around you in real time.
4. Above 85 dB a red warning appears.
5. Tap "Stop measuring" at any time. The microphone is released when you stop.

Readings are a guide only — microphone sensitivity differs between phones, and most phones adjust it automatically. Use a dedicated sound level meter when you need an accurate measurement.

A phone microphone is built for voice, not for measuring sound. Three things limit the accuracy of any browser or app decibel meter:

• Sensitivity varies from model to model, so the same room can read several dB apart on different phones.
• Automatic gain control on many phones turns quiet sounds up and loud sounds down, which flattens the reading.
• A professional meter also applies a frequency weighting (dBA) that matches how the ear hears; this page shows a simple level without that weighting.

For that reason the number is best used to compare — this room against that room, before against after — rather than as an absolute figure.

What counts as "loud" or "quiet" differs from person to person, so a number gives you something to go on. Here are some common uses.

Checking a baby's room or nursery

If you want to know whether a room is calm enough for a baby to sleep, measure it. As the chart shows, around 40 dB — a quiet library — is a level people tend to find quiet. If the air conditioner or a fan bothers you, try the reading in the room itself.

Understanding your workplace noise

Call centres, workshops and open-plan offices can be loud. Knowing roughly how many decibels you work in helps you decide when to take breaks or whether earplugs are worth it. Take particular care if you spend long hours above 85 dB.

Getting a feel for everyday or neighbour noise

When you wonder whether the noise next door is really loud, or whether your own is, a rough number is a useful starting point. Because this is a simple phone-microphone measurement, it cannot serve as legal evidence or an official standard. For a serious dispute, contact your local authority or a professional noise surveyor.

Concerts, events and sports

Live music, festivals and stadiums can stay loud for a long time. The warning above 85 dB is a cue to step back, take a break or put in earplugs.

Cars and engine noise

Compare the cabin with the windows up and down, or before and after adding sound insulation, and the difference in insulation shows up as a number.

Libraries, cafés and study spaces

If you concentrate better in a quiet place, compare the level in a café, a library and a study room to find the environment that suits you.

The figures here are general guides only. They are not official limits set by local regulations or by a venue's rules. If you need an official standard, check with a professional noise surveyor or your local authority.