Sound Decibel Meter
Free online sound level meter. Measure noise in decibels (dB) with your phone or laptop microphone. Runs in the browser, nothing is recorded.
No reading yet
Press start and allow microphone access
- Average
- —dB
- Peak
- —dB
- Minimum
- —dB
- Elapsed
- —s
Phone and laptop microphones have no fixed reference, so absolute values are an estimate. Place a real sound level meter next to this device, play a steady sound, and move the slider until both agree. The setting is saved in your browser.
Decibel levels chart: how loud is 40, 70 or 100 dB?
Decibels are logarithmic: every 10 dB is roughly twice as loud to the ear and ten times the sound energy.
| Level | Example | Band |
|---|---|---|
| 10 dB | Breathing, rustling leaves | Quiet |
| 20 dB | Whisper, quiet library | Quiet |
| 30 dB | Quiet bedroom at night | Quiet |
| 40 dB | Quiet office, refrigerator hum | Quiet |
| 50 dB | Light rain, moderate rainfall | Moderate |
| 60 dB | Normal conversation, dishwasher | Moderate |
| 70 dB | Vacuum cleaner, busy street | Loud |
| 80 dB | Alarm clock, city traffic inside a car | Loud |
| 90 dB | Lawn mower, motorcycle | Harmful over time |
| 100 dB | Subway train, hand drill | Harmful over time |
| 110 dB | Rock concert, chainsaw | Harmful over time |
| 120 dB | Thunderclap, ambulance siren nearby | Harmful over time |
- Quiet: 0–50 dB
- Moderate: 50–70 dB
- Loud: 70–85 dB
- Harmful over time: 85+ dB
How to measure decibels with your phone or laptop?
Use this page as a dB meter, SPL meter or noise monitor. It works on iPhone, Android, Mac and Windows with no app to install, and the steps below give the most reliable reading.
- Allow the microphone. Your browser shows a permission prompt the first time. The site needs a secure (HTTPS) connection for this to work.
- Point the microphone at the source. Keep your hand and any case away from it and hold the device at the position where you want to know the level.
- Wait a few seconds. The large number follows sound with a fast response. Use Average for a steady figure and Peak for the loudest moment.
- Calibrate if you can. If you have access to a real sound level meter, use the calibration slider so both agree, and the offset is remembered on this device.
Decibel meter FAQ: common questions about noise levels
How does the online decibel meter work?
The page reads your microphone with the Web Audio API and converts the signal to decibels many times per second. Everything runs on your device. Nothing is recorded or uploaded.
Can I use my phone as a dB meter, and how accurate is it?
Yes. It works in any modern browser on iPhone, iPad and Android over HTTPS, with nothing to install. Expect readings within a few decibels of a real meter once calibrated. Phone microphones cannot measure much below 30 dB or above about 105 dB. For legal or medical purposes use a certified sound level meter.
Why does a silent room not read 0 dB?
0 dB is the threshold of hearing, and 20 dB is a whisper. Fridges, ventilation and the microphone’s own noise put a quiet room at 25 to 40 dB, which is the lowest reading you should expect.
Is 40 dB loud for sleeping?
No. 40 dB is a quiet office or fridge hum, and the WHO recommends bedrooms stay below 30 dB steady and 45 dB for single events. A fan at 50 dB is fine for most people. 70 dB, a vacuum cleaner or loud TV, will wake almost anyone.
Is 70 dB loud, and what noise level is safe?
70 dB is a vacuum cleaner or busy street: loud but not harmful. 60 dB is normal conversation and 80 dB is heavy traffic. Hearing damage starts above 85 dB over a full day, and the safe time halves every 3 dB, so 100 dB is risky within 15 minutes.
What dB is a gunshot, and can a human survive 200 dB?
A gunshot is 140 to 175 dB at the shooter’s ear, enough to cause permanent damage from a single shot. 200 dB is not survivable: sound in air tops out near 194 dB, and anything louder is a blast wave that causes fatal lung injury.
What do Average, Peak and Minimum mean, and is the reading A-weighted?
The large number follows the sound with a fast 125 ms response. Peak is the loudest instant, Minimum the quietest, and Average the energy-equivalent level (Leq) for the session. The reading is unweighted, so a dBA meter will show slightly lower values for low-frequency noise.
Can I use this as a noise meter for the classroom?
Yes. Open the page on the classroom computer, press Start and leave the tab on the projector or a shared screen. The colour band and level graph show the class when the room gets too loud, and no account, install or recording is involved.
Is this a sound test or a microphone test?
It is a sound level meter, not a speaker test. It measures how loud the room is in decibels using your microphone. Because the reading moves as soon as you speak, it also confirms that your microphone is working and picked up by the browser, but it does not play test tones or check your speakers.
Do I need a sound level meter app?
No. This free decibel meter runs in the browser on iPhone, iPad, Android, Mac and Windows, so there is nothing to install and no permissions beyond the microphone prompt. Add the page to your home screen if you want it to open like an app.