Measure the sound level in decibels
Your browser will ask to use the microphone. Nothing is recorded or uploaded — the sound is only measured.About the decibel meter
How loud is your room, your street or your music? This free decibel meter listens through the microphone of your phone, tablet or computer and shows the sound level in dB, live. It also shows the highest level and the average since you started.
Be aware of one thing: this is an estimate. A real sound level meter has a calibrated microphone. A phone or laptop microphone is not calibrated, and every device hears a little differently. The number is good for comparing — this room against that one, before and after, louder or quieter — but it can be 10 dB or more away from a real meter. If you have a real meter or a known sound, you can match the reading with the calibration offset.
Nothing is recorded. The page measures how loud the sound is and throws the sound away at once.
Features
- Live dB number — a big reading that updates four times a second, easy to read
- Max and average — the highest level and the true average (Leq) since you started or reset
- Colour bar from 20 to 120 dB — green, yellow when it gets close to your limit, red above it
- Your own limit — set "too loud above" from 40 to 110 dB and count how often it was passed
- Calibration offset — move the reading up or down by up to 30 dB to match a real meter
- Full screen — a big display for a room, a rehearsal or a party
- Private — nothing is recorded; your settings stay in this browser
How accurate is a phone decibel meter?
Every microphone turns sound into numbers in its own way, and the computer or phone adds its own volume setting on top. A browser cannot know how loud a number really is in the room. So this page starts from a fixed point — the loudest sound the microphone can send reads about 90 dB — and adds your offset.
What that means for you:
- Differences are useful. If the reading goes up 10 dB, the sound really got a lot louder
- The exact number is not certain. Two phones in the same room can show numbers 10 dB apart
- Very quiet places read too high: the microphone's own hiss sets a floor
- Very loud sounds stop near 90 dB (plus your offset), because the microphone cannot send more
- No frequency weighting. Real meters usually show dBA, which counts deep sounds less, like the ear does. This page counts all frequencies the same, so a deep hum reads higher here than on a dBA meter
For work safety, hearing protection rules or anything legal, use a certified sound level meter.
Using the calibration offset
If you can borrow a real sound level meter:
- Put both side by side, the same distance from a steady sound (a fan, a running tap or rain noise from a speaker)
- Read both numbers
- Move Calibration offset until this page shows the same number as the real meter
The offset is saved in this browser, so the next time you open the page on the same device it starts with your setting. Each device needs its own offset.
Typical sound levels
Rough values, to give you a feeling for the numbers. Real sounds vary a lot with distance.
| Sound | About |
|---|---|
| Whisper at 1 metre | 30 dB |
| Quiet room at night | 30–40 dB |
| Quiet office, fridge hum | 40–50 dB |
| Normal conversation at 1 metre | 60 dB |
| Busy restaurant, TV at normal volume | 60–70 dB |
| Vacuum cleaner | 70–75 dB |
| Busy street traffic | 70–85 dB |
| Lawn mower, blender | 85–95 dB |
| Loud concert or club | 100–110 dB |
Decibels in a nutshell
Decibels count in steps of ten times, not in plain numbers:
- +3 dB = twice the sound energy (for example two equal machines instead of one)
- +10 dB = ten times the sound energy, which most people hear as about twice as loud
- +20 dB = a hundred times the sound energy
Because of this, the average is not the middle of the numbers. If a room is at 60 dB for half the time and at 70 dB for the other half, the average is 67.4 dB, not 65 dB — the loud half counts much more. The page works out this energy average for you (it is called Leq).
Frequently asked questions
Is this a real decibel meter?
It measures the sound level with your microphone, but the microphone is not calibrated. The number is an estimate that can be 10 dB or more off. It is good for comparing; for exact or legal measurements use a certified meter.
Why does it show a different number than my phone app?
Every app starts from its own guess, and every microphone hears differently. Use the calibration offset to match a meter you trust.
What is the difference between dB and dBA?
dBA counts deep and very high sounds less, the way the ear hears them. Most real meters show dBA. This page shows the level without that weighting, so deep sounds read a bit higher here.
Why does it never go above about 90 dB?
That is the loudest sound the microphone can pass on before it clips. Above that, the number stops rising. The offset moves this limit too.
What do Max and Average mean?
Max is the highest reading since you pressed Start or Reset max and average. Average is the energy average (Leq) over the same time. Both use the offset you set.
Is anything recorded?
No. Nothing is recorded, saved or sent. The page only measures how loud the sound is, and throws the sound away at once.
Related tools
- Classroom Noise Meter — a big green, yellow and red display for a class
- Microphone Test — check that your microphone works
- Spectrogram — see which frequencies make the noise
- Tone Generator — play a steady tone to compare two places
- White Noise — a steady sound to cover noise
How to use it
- Press Start the decibel meter and allow the microphone
- Hold the device still, with the microphone pointing at the sound
- Read the big number; Max and Average grow while you measure
- Set Too loud above to your limit; the screen turns red above it
- If you have a real meter, match the reading with the Calibration offset
- Press Reset max and average to start a new measurement, and Stop when you are done
