Clip
—dBA
Tap Start to begin
0 dB407085120 dB
Silent Quiet Moderate Loud Dangerous
Min
— dB
Avg (Leq)
— dB
Max
— dB
Peak
— dB
Recent Sound Levels (60s) dB over time
Frequency Spectrum 20 Hz – 20 kHz

Reference Sound Levels

What Is This Sound Meter?

This is a free browser-based sound level meter that uses your device's built-in microphone to measure and display noise levels in real time. It works directly in your browser — there is nothing to install and no account required. Just tap Start and the meter begins analyzing the sound around you.

The tool captures audio through the Web Audio API, runs a Fast Fourier Transform (FFT) with 4096 sample points to break the signal into individual frequencies, then calculates the overall loudness using RMS (Root Mean Square) amplitude. The result is converted to an estimated decibel reading and displayed along with a live history graph, frequency spectrum, and running statistics.

All processing happens locally on your device. No audio is ever recorded, stored, or sent anywhere.

How Does It Measure Sound?

When you tap Start, the browser asks for microphone permission. Once granted, the meter captures a continuous stream of audio samples — thousands per second. Here is what happens behind the scenes:

  1. Microphone capture — your browser accesses the device microphone and streams raw audio data.
  2. RMS calculation — the Root Mean Square of the audio samples is computed to find the average signal power, which gives a stable loudness reading rather than reacting to every single sample.
  3. FFT frequency analysis — a 4096-point Fast Fourier Transform splits the audio into over 2000 frequency bins, showing exactly which frequencies (bass, mid, treble) are present.
  4. Frequency weighting — standard A-weighting or C-weighting curves are applied using the FFT data so the reading matches how the human ear actually perceives sound.
  5. dB estimation — the raw digital level (dBFS) is shifted by a calibration offset to produce an approximate dB SPL reading you can compare to real-world reference levels.
Good to know: The raw reading is dBFS (decibels relative to full scale), where 0 dBFS means the microphone is at maximum. An offset is added to convert this to an estimated dB SPL (sound pressure level) so the numbers match what you would see on a handheld meter. You can fine-tune this offset in Settings → Calibration.

Why Use a Browser Sound Meter?

Home & Sleep

Check if your bedroom is below the recommended 30–40 dB for good sleep. Compare noise with windows open vs. closed. Test how loud appliances really are.

Work & Study

Find peak noise hours in an open office. Measure background noise before video calls. Document workplace noise levels for discussions with management.

Music & Events

Keep your speaker volume in a safe 70–80 dB range for daily listening. Check if a concert or venue exceeds 100 dB. Measure headphone listening levels.

Health Awareness

Prolonged exposure above 85 dB can cause permanent hearing damage. Use the meter to stay aware of your environment and protect your hearing over time.

What Each Setting Means

Frequency Weighting (dBA / dBC / dBZ)

dBA (A-weighted) filters the sound the same way your ears do — it reduces very low and very high frequencies that humans hear less clearly. This is the most common setting and the one to use for everyday noise like conversation, traffic, or appliances.

dBC (C-weighted) keeps more of the low-frequency (bass) content in the reading. Use this when measuring loud bass-heavy sources like subwoofers, construction machinery, or concerts.

dBZ (Z-weighted / flat) applies no filtering at all — every frequency counts equally. This shows the raw signal and is mostly useful for technical analysis.

Calibration Offset

Every microphone has different sensitivity. The calibration slider lets you shift all readings up or down by up to 30 dB so your meter roughly matches a trusted reference device. This does not make the meter laboratory-accurate, but it makes your readings more meaningful for comparisons.

History Window (30s / 60s / 120s)

Controls how far back the history graph shows. A 30-second window reacts quickly to changes. A 120-second window is better for seeing longer trends and averaging out brief spikes.

Smooth Display

When enabled, the number on screen interpolates smoothly between readings instead of jumping. This makes it easier to read in real time. Turn it off if you want to see every rapid change instantly.

Peak Hold (3s)

Keeps the loudest reading visible in the Peak stat for 3 seconds before it resets. Useful for catching brief loud sounds (door slams, honks) that you might otherwise miss.

Microphone Source

If your device has multiple microphones (for example, a laptop with built-in and external mics), you can switch between them here. The list populates after you start measuring.

How to Calibrate for Better Accuracy

Without calibration, this meter shows an estimated dB level based on a general offset. To improve accuracy for your specific device, follow these steps:

  1. Get a reference — either a dedicated handheld sound level meter, or a phone app that has been calibrated, or a known steady sound source.
  2. Place both devices side by side, same distance from the sound source.
  3. Play a steady noise (a fan, white noise, or a 1 kHz tone works well — avoid music or speech since they fluctuate).
  4. Read the average level on your reference device.
  5. Open Settings → Calibration Offset and adjust the slider until this meter shows roughly the same average.
  6. The offset is saved automatically and applies every time you use the meter.
Keep in mind: Calibrating with one sound at one distance does not guarantee accuracy for all sounds and distances. Microphone frequency response varies by device. Treat the calibrated reading as a good estimate, not a certified measurement.

What Affects Your Readings

  • Microphone quality — phone and laptop mics have different sensitivity and frequency response than professional measurement microphones.
  • Operating system gain control — many devices automatically adjust microphone volume (AGC). This can make quiet sounds seem louder and loud sounds seem quieter. Disable it in system settings if possible.
  • Noise suppression — browsers and operating systems sometimes filter out background noise. This helps on calls but hurts measurement accuracy. Disable it when you can.
  • Distance and angle — sound intensity drops with distance. Moving just one meter closer can change the reading noticeably. Always note your distance when comparing readings.
  • Room reflections — small rooms with hard walls can inflate readings because sound bounces and builds up. Larger or softer-furnished rooms give lower readings for the same source.
  • Background noise — if the ambient noise floor is high, it will add to your measurement. Measure in the quietest conditions possible for the most accurate result.
Best practice: Measure for at least 30–60 seconds and use the average (Leq) value rather than a single snapshot. Repeat 2–3 times and compare. Keep your device still and uncovered — do not block the microphone with your hand or a case.

Safe Noise Exposure Times

According to NIOSH guidelines, every 3 dB increase above 85 dB cuts the safe daily exposure time in half. This is known as the 3 dB exchange rate.

Noise Level Safe Exposure Example
70 dB Unlimited Normal conversation
85 dB 8 hours Busy restaurant, blender
88 dB 4 hours Heavy city traffic
91 dB 2 hours Lawn mower, power drill
94 dB 1 hour Belt sander, loud music
100 dB 15 minutes Motorcycle, chain saw nearby
110 dB ~2 minutes Rock concert front row
120+ dBImmediate risk Siren, fireworks at close range

Use the average (Leq) reading, not brief peaks, when estimating your exposure. If you are regularly near 85 dB or above, consider ear protection.

Troubleshooting Common Issues

The meter will not start or shows no reading

  • Check that microphone permission is allowed in your browser settings. Reload after changing it.
  • Make sure no other app or tab is using the microphone at the same time.
  • On iOS, Safari sometimes blocks microphone access silently — go to Settings → Safari → Microphone and enable it for this site.
  • Try closing and reopening the browser completely.

Readings seem too high or too low

  • Adjust the Calibration Offset in Settings. This is the most common fix.
  • Check your OS microphone input volume — some systems default to a very high or very low gain.
  • Make sure noise suppression and auto-gain are disabled in system audio settings.
  • Move closer to or farther from the sound source and observe how the reading changes.

The meter stops unexpectedly

  • Some browsers suspend audio when the tab goes to background. Keep the tab in the foreground while measuring.
  • On mobile, battery saver modes can interrupt microphone access. Disable power saving while measuring.
  • If the page crashes on older devices, try using the meter without other heavy tabs open.

Frequently Asked Questions

It provides a good estimate for everyday use. Accuracy depends on your device microphone, operating system settings, and whether you have calibrated the offset. It will not match a professional Class 1 meter, but for comparing noise levels, spotting loud environments, and general awareness, it works well. Think of it like a kitchen scale — useful for daily purposes, not for a laboratory.
No. All audio processing happens entirely within your browser on your device. The raw microphone signal is analyzed in real time and immediately discarded. Nothing is recorded, stored, uploaded, or accessible to anyone. Your microphone permission can be revoked at any time in browser settings.
dBFS (decibels relative to full scale) is the raw digital level from the microphone, where 0 dBFS is the loudest the mic can capture before clipping. dB SPL (sound pressure level) is the physical acoustic pressure measured with calibrated equipment. This tool measures dBFS internally and adds a calibration offset to estimate dB SPL. The number you see on screen is the estimated SPL value.
Yes. It works in Safari on iOS and iPadOS. You will need to allow microphone access when prompted. If it does not work, go to iOS Settings → Safari → Microphone and make sure it is enabled. Note that iOS sometimes applies automatic gain control which can affect accuracy — if readings seem off, try adding +5 to +10 dB to the calibration offset.
A-weighting is a standard filter that adjusts the reading to match the way human ears perceive sound. We hear mid-range frequencies (around 1–4 kHz) much better than very low or very high frequencies. A-weighting reduces the contribution of those harder-to-hear frequencies so the dBA number reflects perceived loudness. It is the most widely used weighting for environmental and occupational noise.
The World Health Organization recommends keeping nighttime noise below 40 dB for uninterrupted sleep, with 30 dB or less being ideal. If your bedroom measures above 40 dB, consider using earplugs, a white noise machine, or addressing the noise source (closing windows, adding soft furnishings to absorb sound).
Sustained exposure above 85 dB can damage hearing over time. At 100 dB, safe exposure drops to just 15 minutes per day. Above 120 dB there is risk of immediate hearing damage. If you need to shout to be heard by someone a meter away, the environment is likely above 85 dB and you should consider ear protection.
Real sound levels do change rapidly — that is normal. Enable the Smooth Display option in Settings to reduce visual jitter. For a more stable number, look at the Average (Leq) stat which uses energy-based averaging over the entire measurement session. Brief spikes from coughs, door slams, or traffic will show up in the Max and Peak values but will not significantly affect the average.

Privacy & Data Security

Your privacy matters. Here is exactly what happens with your data:

  • No audio recording — the microphone signal is analyzed frame-by-frame and immediately discarded. Nothing is saved.
  • No server uploads — all computation happens in your browser. There is no backend receiving audio data.
  • No tracking of measurements — your dB readings, statistics, and history are kept only in browser memory and disappear when you close the tab.
  • Settings stored locally — theme preference and calibration offset are saved in your browser's localStorage only. No cookies or external analytics track your usage.