Online Decibel Meter
Measure noise in decibels (dB) right in your browser. A free decibel meter app for iPhone, Android and computers that needs no download, with professional A, C and Z weighting, live history, calibration and export.
Press Start and allow microphone access.
- Min
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- Avg
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- Max
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- Peak
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- Time
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How to use this decibel meter
- 1
Press Start
Allow microphone access when your browser asks. Nothing is recorded or uploaded.
- 2
Read the level
The big number is the current sound level in dB(A). Min, Avg (Leq), Max and Peak update live.
- 3
Calibrate (optional)
Match a reference meter once for lab-like accuracy. Your calibration is saved on this device.
- 4
Save or share
Export a CSV log, save a snapshot image, or share your result with a link.
A professional sound level meter, without the price tag
A, C & Z frequency weighting
True IEC 61672 weighting filters, not a rough approximation. Use A for everyday noise, C for music and bass, Z for a flat response.
Leq, Max, Min & Peak
Energy-averaged Leq is what professionals report. Max and Min follow the time-weighted level; Peak captures the loudest instant.
Live timeline & spectrum
See how noise changes over up to 15 minutes, or switch to an octave-band spectrum to find out which frequencies dominate.
Calibration that sticks
Match a reference once and your offset is saved per microphone, so every future session is accurate.
Full screen & screen-on
A huge, glanceable read-out for stages, gyms and classrooms. The screen stays awake while you measure.
Private by design
Audio is processed in real time on your device. We never record, store or transmit your sound.
How loud is it? Common decibel levels
Use these everyday sounds as a reference for what your meter shows.
Decibel Chart →Recommended noise limits (WHO)
The World Health Organization recommends the following maximum average levels to protect sleep and wellbeing.
| Setting | Recommended limit | Why |
|---|---|---|
| Bedroom at night | 30 dB(A) average, 45 dB(A) max | Undisturbed sleep |
| Road traffic outside (night) | 45 dB Lnight | Sleep disturbance |
| Road traffic outside (24 h) | 53 dB Lden | Annoyance, heart health |
| Outdoor living areas (day) | 50–55 dB(A) | Moderate to serious annoyance |
| Classrooms | 35 dB(A) background | Speech intelligibility |
| Leisure (concerts, clubs) | 70 dB(A) yearly average | Hearing protection |
Sources: WHO Guidelines for Community Noise (1999) and Environmental Noise Guidelines (2018). Local laws differ.
Are decibel meter apps accurate?
Your device microphone is surprisingly capable, but it was designed for voice, not measurement. Without calibration, most phones and laptops read within about ±3–7 dB in the 40–90 dB range. After a one-time calibration against a reference meter, accuracy of ±1–2 dB is realistic for steady sounds.
We disable the browser’s echo cancellation, noise suppression and automatic gain control, which would otherwise distort measurements. Very quiet rooms (below ~30 dB) are limited by the microphone’s self-noise, and very loud sounds (above ~110 dB) may clip.
For legal disputes, workplace compliance or certified reports, use a Class 1 or Class 2 sound level meter. For everyday checks, such as a noisy neighbour, a loud gym class or a baby’s white-noise machine, this tool gives you a trustworthy, instant answer.
Is there a free decibel meter app? You’re using one
There is nothing to install and nothing to pay for. It works on iPhone, Android, Windows, Mac and Chromebook, and you can add it to your home screen to use it like a native sound meter app, even offline.
Unlike many free noise meter apps, there are no pop-ups, no tracking of your audio and no premium paywall for features like weighting, calibration or export.
Noise & Sound Level Guides
Guides →Does iPhone Have a Decibel Meter? How to Measure dB on iPhone
Does iPhone have a decibel meter? Learn what Apple shows for headphones, what measures room noise, and how to measure dB on iPhone.
How to Use a Decibel Meter
How to use a decibel meter or online sound meter: choose weighting, position the mic, calibrate, read Leq/Max/Peak, and document noise readings.
What Is a Decibel Meter?
What is a decibel meter? Learn what a decibel meter is called, how it measures sound pressure level, key settings, types, and how to choose one.
Are Decibel Meter Apps Accurate? What to Expect
Are decibel meter apps accurate? Learn decibel meter app accuracy limits, how calibration helps, and how to choose a free decibel meter app.
How to Measure Decibels With Your Phone
How to measure decibels with a phone, improve app accuracy, calibrate readings, and avoid common mistakes in real-world noise checks.
How to Measure Neighbor Noise for a Complaint
How to measure neighbor noise, keep a useful noise diary, understand common complaint levels, and document sound without overclaiming.
What Is a Decibel? The dB Scale Explained
What is a decibel? Learn the logarithmic dB scale, dB SPL, dBA, adding sound sources, distance loss, and common measurement traps.
dBA vs dBC: A, C, and Z Weighting Explained
dBA vs dBC explained clearly, with IEC 61672 weighting values, Fast and Slow response, Leq, Lmax, Lpeak, and what to use when measuring.
Noise Level for Sleeping: How Many dB Is Safe?
Noise level for sleeping explained with WHO bedroom guidance, white noise machine safety, and a practical way to measure night sound.
Frequently asked questions
Is there a free decibel meter app?
Yes, this page is one. It works like a decibel meter app on iPhone, Android and computers without a download, and every feature (weighting, calibration, charts, CSV export, full screen) is free with no sign-up. Add it to your home screen to use it offline.
What is a decibel meter?
A decibel meter measures how loud a sound is in decibels (dB). Its formal name is a sound level meter (SLM); it is also called an SPL meter, noise meter, dB meter or sonometer.
Do you record or upload my audio?
No. Sound is analysed in real time inside your browser using the Web Audio API. No audio ever leaves your device.
What is dB(A)?
dB(A) is a decibel reading filtered to match how human ears perceive loudness. It is the standard for environmental and workplace noise.
What does Leq mean?
Leq (equivalent continuous level) is the energy average over the measurement period. It represents fluctuating noise as a single steady level and is what regulations usually refer to.
Why is the reading different from my friend’s phone?
Microphones differ in sensitivity. Calibrate each device against the same reference to get matching results.
Does iPhone have a decibel meter?
Not a built-in one for room noise: the Control Center Hearing feature only shows headphone levels, and the Noise app is on Apple Watch. This online decibel meter works on iPhone in Safari or Chrome (iOS 14.5+) with no download; calibration is recommended because iOS applies some audio processing.
Are decibel meter apps accurate?
Good phone meters are usually within about 3–7 dB between 40 and 90 dB without calibration, and around 1–2 dB for steady sounds after calibrating against a reference meter. For legal or workplace compliance, use a Class 1 or Class 2 sound level meter.
What noise level is harmful?
Long exposure above 85 dB(A) can damage hearing. NIOSH recommends no more than 8 hours at 85 dB(A), halving the time for every 3 dB increase.
Can I use it without internet?
Yes. After your first visit, install it from your browser menu (“Add to Home Screen” / “Install app”) and it works offline.