How to use the decibel meter
- Tap Start measuring, allow the microphone, and point the bottom of your phone at the sound.
- Read the big number. It's the current level in dBA, the scale used for noise and hearing safety.
- Leave it running. Average shows the true energy average (Leq) and Max the loudest moment since you started.
- Tap Export CSV to save a second-by-second log, or Share to send a summary.
What it measures
Real A, C and Z weighting
The microphone signal runs through digital filters built to the IEC 61672 curves, sample by sample. Not an estimate from a few FFT bins.
True average (Leq)
Decibels can't be averaged like ordinary numbers. Average here is the energy average, the figure that noise rules and regulations use.
Hearing-safety dose
See how much of a safe daily noise allowance you've used, and how long the current level is safe for, using the NIOSH limit.
Spectrum and dominant tone
One-third-octave bars show whether a noise is a low hum or a high whine, with the strongest frequency and its musical note.
Logs you can keep
Export every second as a CSV file with A, C and Z levels, max and peak. Useful for a noise complaint or a report.
Nothing is recorded
The audio is analysed on your device and thrown away immediately. No sound ever leaves your phone.
How loud is that? Common sounds in decibels
Typical levels at a normal listening distance. Real sounds vary a lot with distance and surroundings.
| Level | Typical sound | How it feels |
|---|---|---|
| 0 dB | The threshold of hearing | Very quiet |
| 10 dB | Normal breathing | Very quiet |
| 20 dB | Rustling leaves | Very quiet |
| 30 dB | A whisper | Very quiet |
| 40 dB | A quiet library | Quiet |
| 50 dB | A quiet office | Quiet |
| 60 dB | A normal conversation | Moderate |
| 70 dB | A vacuum cleaner | Moderate |
| 80 dB | Heavy city traffic | Loud |
| 85 dB | A kitchen blender | Loud |
| 90 dB | A lawn mower | Very loud |
| 100 dB | A motorbike passing | Very loud |
| 110 dB | A rock concert | Dangerous |
| 120 dB | A thunderclap | Dangerous |
| 140 dB | Fireworks up close | Dangerous |
Every 10 dB sounds roughly twice as loud, so a 70 dB vacuum cleaner seems about twice as loud as a 60 dB conversation and four times as loud as a 50 dB office.
What is a decibel?
A decibel (dB) compares a sound's pressure with the quietest sound a healthy young ear can hear, which is set as 0 dB. Because the ear handles an enormous range, from a pin drop to a jet engine, the scale is logarithmic: each step of 10 dB is ten times more sound energy.
dBA, dBC and dBZ: which weighting should I use?
Your ears are far less sensitive to deep bass and very high treble than to the middle of the range. Frequency weighting adjusts the meter to match.
dBA: for people
Follows the ear at everyday levels. Use it for noise complaints, workplaces, traffic, sleep and hearing safety. It's the default.
dBC: for loud and bassy sound
Almost flat, trimming only the extremes. Use it for concerts, home cinema, subwoofers and peak levels.
dBZ: unweighted
No weighting at all, within the limits of the microphone. Useful for comparing equipment or spotting rumble.
A big gap between the C and A readings means the noise is mostly bass: think of a neighbour's music through a wall, a ventilation fan or a truck idling outside. The Bass content line under the meter shows that gap.
How loud is too loud?
Hearing damage depends on both level and time. Above 85 dBA, the safe time halves with every 3 dB.
| Level | Safe time per day (NIOSH) |
|---|---|
| 85 dBA | 8 h 0 min |
| 88 dBA | 4 h 0 min |
| 91 dBA | 2 h 0 min |
| 94 dBA | 1 h 0 min |
| 97 dBA | 30 min 0 s |
| 100 dBA | 15 min 0 s |
| 103 dBA | 7 min 30 s |
| 106 dBA | 3 min 45 s |
| 109 dBA | 1 min 53 s |
| 112 dBA | 56 s |
| 115 dBA | 28 s |
This is the US National Institute for Occupational Safety and Health (NIOSH) recommendation. The US workplace law (OSHA) is less strict: 90 dBA for 8 hours, halving every 5 dB. The EU requires employers to act from 80 dBA over a working day.
How accurate is a phone decibel meter?
More accurate than most people expect, after calibration. Phone microphones are built for speech, so they're best between about 40 and 100 dB and in the middle of the frequency range. A study by NIOSH found the best smartphone apps within about 2 dBA of a professional meter once calibrated.
Out of the box, every phone model is different, so dB Meters starts from an estimate and labels it as one. Very quiet rooms may read a little high because of the microphone's own noise, and very loud sound may hit the microphone's limit; the meter warns you when that happens. For legal or workplace measurements, use a certified Class 1 or 2 meter.
Frequently asked questions
Is this decibel meter free?
Yes, with no sign-up and no time limit. Ads around the page keep it free.
Does it record audio?
No. The microphone signal is analysed on your device and thrown away within milliseconds. Only the numbers are kept, and only on your device.
Why does my reading differ from another app?
Every app and phone starts from a different calibration, and some apps use averaging or weighting that isn't standard. Calibrate against a reference meter and the readings will agree closely.
Is 85 dB loud?
Yes. 85 dBA is the level at which hearing damage becomes possible with long exposure. NIOSH recommends no more than 8 hours a day at 85 dBA, and only 15 minutes at 100 dBA.
What's the difference between dB and dBA?
dB alone is an unweighted sound level. dBA applies A-weighting, which reduces bass and very high sounds the way the human ear does. Noise limits are almost always given in dBA.
Does it work on iPhone and Android?
Yes, in Safari, Chrome, Edge, Firefox and Samsung Internet. It also works on laptops and desktops with a microphone.