Decibel Meter Online – Free Sound Level Meter
Room noise estimatePress start to measure
- 30–40 dB: quiet bedroom
- 60 dB: normal conversation
- 85 dB+: limit your exposure
Decibel Meter Online (Sound Level Meter)
Measure how loud your environment is with this online decibel meter. Allow microphone access to see live, minimum, average and maximum sound levels in dB plus a history graph.
Live Reading
A smoothed dB estimate updates ten times a second from your microphone.
Min · Avg · Max
Track the quietest, average and loudest moments of a session.
Calibration
Adjust the offset against a reference meter for better estimates.
How to
Measure Decibels
- 01
Click Start meter and allow microphone access
- 02
Hold the device still, mic toward the source, at arm's length
- 03
Wait 10–30 seconds and read the average
- 04
Optionally calibrate against a reference meter with the offset slider
Sound level guide
| dB | Example | Risk |
|---|---|---|
| 30 | Whisper, quiet bedroom | None |
| 40 | Library | None |
| 50–60 | Office, conversation | None |
| 70 | Vacuum cleaner | Annoying over time |
| 85 | Heavy traffic | Risk after ~8 h/day |
| 94 | Motorcycle, power tools | Risk after ~1 h |
| 100 | Nightclub, loud headphones | Risk after ~15 min |
| 110+ | Concert front row | Damage within minutes |
Safe exposure time by decibel level
Under NIOSH guidance, safe daily exposure halves for every 3 dB above 85 dBA: 85 dB = 8 h, 88 = 4 h, 91 = 2 h, 94 = 1 h, 97 = 30 min, 100 = 15 min.
Safe listening at a glance
| Level | Example | Guideline |
|---|---|---|
| 60 dB | Conversation | Safe |
| 85 dB | Busy traffic | About 8 hours per day |
| 94 dB | Loud concert edge | About 1 hour |
| 100 dB | Nightclub | About 15 minutes |
See the full decibel levels chart.
Accuracy, limitations and calibration
Phone and laptop mics aren't lab instruments: they have uneven frequency response, may apply processing, and saturate around 95–110 dB. This meter requests raw input (no echo cancellation, noise suppression or auto-gain) and adds a calibration offset to the measured dBFS level. The 94 dB default is a starting point; expect ±5–10 dB without calibration. To calibrate, place your device beside a certified meter, play steady noise and adjust the offset until readings match. For legal, workplace or medical decisions use a Class 1/2 meter.
dB, dBA and dBC explained
Decibels are logarithmic: +10 dB sounds about twice as loud; +3 dB doubles acoustic energy. dBA de-emphasises low and very high frequencies to match hearing and is used in regulations; dBC is flatter, for bass-heavy sound. This meter shows an unweighted estimate.
Practical uses
- Check bedroom noise for sleep (WHO suggests under ~30 dB at night).
- Keep home-cinema and headphone levels safe.
- Document neighbour or traffic noise patterns.
- Compare fans, PCs and appliances.
- Monitor classroom and office noise.
How it works
The browser captures microphone audio via the Web Audio API, computes the RMS level of each 4096-sample block, converts it to dBFS and adds the calibration offset to estimate sound pressure level. Readings are smoothed and updated 10 times per second. Nothing is recorded or uploaded.
Reading the meter
What this tool does
Estimates sound level from your microphone with live, min, average and max.
Colour-coded display
Green is comfortable, amber is loud, red is risky for long exposure.
Tips for better readings
Remove the case, hold still, measure for at least 60 seconds.
Comparisons
Use the reading for controlled comparisons
Compare the same spot before and after a change.
A quick guide to measuring sound in your browser
- Allow the microphone and remove the phone case.
- Hold the device at arm's length, pointing at the source, or place it where people's ears would be.
- Watch for 30–60 seconds; average readings are far more reliable than a single glance.
- Note min, average and max. Compare readings from the same device only.
Related guides and fixes
Learn more in these guides: Microphone not working, Microphone settings, Discord mic fixes, Decibel levels chart, What is LUFS.
Frequently Asked Questions
Q.Is this online decibel meter accurate?
It gives a useful estimate: about ±5–10 dB uncalibrated, within a few dB when calibrated for steady sounds.
Q.Why does it need microphone access?
It measures sound via the mic. Audio is processed locally only.
Q.What is a safe decibel level?
Under 70 dB is safe for any duration; from 85 dB limit exposure (8 h at 85 dB, halving every 3 dB).
Q.Why does the reading stop rising at loud sounds?
Device microphones saturate, typically at 95–110 dB.
Q.Does this measure dBA?
It shows an unweighted estimate; use a certified meter for dBA compliance.
Q.Can I use it for a noise complaint?
It helps document patterns, but authorities usually require calibrated equipment.
Q.Why do my phone and laptop read differently?
Different mics and processing. Calibrate each device separately.
Q.How quiet should a bedroom be?
Ideally below 30–35 dB at night.