Decibel Meter: How Loud Is It?

How the decibel meter works

When you tap Start, the page listens to your microphone and measures the energy in the sound many times per second. It converts that into an estimated sound level in decibels, smooths it so the number is readable, and tracks the quietest, loudest and average levels since you started. The sound is analysed in your browser and is never recorded, stored or uploaded.

How loud is loud?

The decibel scale is logarithmic. Every 10 dB increase is roughly twice as loud to your ears and ten times the sound energy. Health guidance generally advises limiting time spent above 85 dB.

Accuracy and calibration

Phone and laptop microphones are built for voices, not measurement, and each model responds a little differently. Readings are estimates, typically within a few decibels of a sound level meter in the middle of the range. If you know the true level of a sound, use the calibration slider to line the readings up. For anything that must hold up legally, such as workplace noise assessments, use a certified meter.

Practical uses

• Noise at home: check traffic or neighbour noise at different times of day before you complain or soundproof.
• Nurseries: keep white noise machines at a gentle level, generally under about 50 dB at the cot.
• Work and hobbies: see whether power tools, workshops or band practice call for ear protection.
• Venues and gyms: compare how loud different rooms or classes are.

For the most consistent results, point the microphone at the sound, keep the device still, and avoid covering the microphone with your hand or a case.