Decibel Meter — Measure Sound Levels in Real Time

A decibel meter, also known as a sound level meter or noise meter, is an instrument that measures the intensity of sound in the air and reports it in decibels (dB). Traditional sound level meters are dedicated hardware devices used by engineers, safety officers, and acousticians. An online decibel meterdoes the same job in your web browser — it uses your device's microphone to capture sound and converts it into a live dB reading in real time. That means you can measure noise levels anywhere, on any phone or laptop, without buying hardware or installing an app.

This free decibel meter is built for everyday use: checking how loud your room actually is, testing speakers, comparing noise in different rooms, monitoring a workplace, or simply satisfying your curiosity about the sounds around you. The readings it produces are useful estimates, not certified laboratory results — you'll find the accuracy details at the bottom of this guide.

What Do Decibels (dB) Mean?

The decibel (dB) is a logarithmic unit that expresses the ratio of a sound pressure level to a reference level. Because the human ear can handle an enormous range of sound intensities — from a whisper to a jet engine — the dB scale compresses that range into practical numbers. A small change on the scale represents a large change in energy: an increase of 10 dB sounds roughly twice as loud, while an increase of 3 dB represents a doubling of sound energy.

Most sound level meters, including this one, also offer frequency weighting. A-weighting (dBA) filters the signal to mirror how the human ear perceives loudness at different frequencies, which makes it the standard measure for noise exposure. This matters because a raw dB reading does not always reflect how loud a sound actually feels.

How Does an Online Decibel Meter Work?

When you press Start Measuring, your browser requests access to the device microphone. The captured audio is processed locally through the Web Audio API — it never leaves your device. The signal is analyzed in real time: the amplitude of the incoming waveform is converted to a sound pressure level and displayed as decibels on your screen. This dB meter shows the current level plus minimum, average, maximum, peak, and Leq (equivalent continuous level) statistics, and lets you switch between fast, slow, and impulse time weighting.

How to Measure Sound With Your Device Microphone

1. Click Start Measuring and allow microphone access when your browser asks for it.
2. Hold your phone or laptop close to the sound source without covering the microphone.
3. Wait a few seconds for the reading to settle, then watch the live dB value and the level bar.
4. Review the statistics panel for minimum, average, and maximum readings, and export them as CSV or JSON if you want a record.

For the most representative results, measure at the spot where people actually sit or stand, point the microphone toward the source, and keep your hand or phone case away from the mic opening.

Understanding Minimum, Average, and Maximum Readings

The minimum reading shows the quietest moment captured, the maximum shows the loudest peak, and the average reflects the typical level over time. The Leq value is especially useful: it represents the average sound energy over the whole session, which is the metric professionals use to assess noise exposure. If the maximum is much higher than the average, you're hearing occasional loud events — claps, doors, or passing vehicles — rather than steady noise.

Why Microphone Permission Is Required

Browsers are required to ask before any website can access your microphone — this is a privacy safeguard built into every modern browser. The permission prompt appears because this decibel meter reads live audio from your device. All processing happens locally: your microphone audio never leaves your device, and nothing is uploaded or recorded. You can read the full details in our privacy policy.

How Accurate Is a Microphone Decibel Meter?

We don't make unrealistic claims. A consumer microphone — especially the small ones inside phones and laptops — is not a professional measurement instrument. Readings can be affected by the microphone hardware itself, your device volume settings, automatic gain control (AGC), noise suppression, echo cancellation, and the acoustics of the room. This tool gives consistent, useful estimates for reference and education, not certified measurements for regulatory compliance. The decibel meter accuracy guide explains every factor in detail.

How to Improve Accuracy

• Follow the step-by-step measuring guide for a repeatable workflow.
• Use the Calibrate button with a known reference sound to apply an offset — see the calibration guide.
• Disable automatic gain control, noise suppression, and echo cancellation if your device allows it.
• Use an external measurement microphone if you need more dependable results.
• Take several measurements from different positions and compare the averages.

For professional or regulatory work, use a certified sound level meter that meets standards such as IEC 61672.

New to sound measurement? The Sound Level Guide explains the decibel scale, weighting curves, and common sounds in dB. You can also compare dB vs dBA, learn aboutnoise exposure, use your phone as a decibel meter, browse the FAQ, or keep a Noise Journal of your measurements.