DecibelwerkKnow exactly how loud it is.
A sound level meter built like studio gear: a backlit VU needle, A, C and Z weighting, and noise logs you can hand to a landlord. Plus a tone generator and a speaker cleaner. All on your iPhone, nothing recorded.
Get notified at launchComing soon to iPhone. The meter will be free.8 h+ NIOSH safe time · normal conversation
Typical levels from the American Academy of Audiology. Real ones depend on distance; that's what the meter is for.
What it does
Measure it. Generate it. Clear it.
Sound level meterA, C and Z weighting, Fast and Slow response, Leq, min, max and the NIOSH safe time for the current level, on a backlit VU needle.
Tone generatorSine, square, sawtooth and triangle from 20 Hz to 20 kHz on a knurled tuning knob. Test speakers, headphones and your hearing range.
Speaker cleanerA pulsed 165 Hz tone that shakes water drops off the speaker grille after a splash, with Apple's own drying advice beside it.
Everything in the app
| Instrument | What it does | Price |
|---|---|---|
| Sound level meter | A-weighted decibel meter with a backlit VU needle, Leq, min, max and the NIOSH safe time. | Free |
| Tone generator | Sine, square, saw and triangle from 20 Hz to 20 kHz on a knurled tuning knob, with a 20 Hz–20 kHz sweep. | Free (sweep with Pro) |
| Speaker cleaner | A pulsed 165 Hz tone for 30 seconds that shakes water drops off the speaker grille. | Free |
| Noise logs and reports | Records the level once a second for up to 8 hours; PDF report with Leq, Max, L10, L90 and dose. | 3 free logs, then Pro |
Decibelwerk Pro saves unlimited noise logs, exports PDF reports and unlocks C and Z weighting, calibration and the sweep. $19.99 once, $9.99 a year, or $1.99 a week.
How long is safe at each level
NIOSH recommends no more than 85 dBA averaged over 8 hours, and halves the time for every 3 dB louder. Last checked November 2026.
| Level | Safe per day (NIOSH) | Sounds like |
|---|---|---|
| 85 dBA | 8 hours | Alarm clock |
| 88 dBA | 4 hours | Lawn mower, power tools |
| 91 dBA | 2 hours | Lawn mower, power tools |
| 94 dBA | 1 hours | Lawn mower, power tools |
| 97 dBA | 30 minutes | Snowmobile, earbuds at full volume |
| 100 dBA | 15 minutes | Snowmobile, earbuds at full volume |
| 106 dBA | 4 minutes | Concert, car horn, sporting event |
How loud is too loud? Or work out any level with the free noise exposure calculator.
It measures. It never records.
Decibelwerk reads the level and throws the audio away. Noise logs keep numbers, once a second, on your phone. Nothing about your home, your gig or your conversation leaves it.
No account, no ads, no email. It works offline too.
Real situations, measured properly
Questions
- Can an iPhone really measure decibels?
- Yes, within limits. Decibelwerk reads the microphone in iOS measurement mode, which switches off the automatic gain that would otherwise flatten loud and quiet sounds. In normal rooms readings are usually within a few dB. It isn't a certified Class 1 or Class 2 meter, and a phone microphone is less reliable below about 35 dB and above about 110 dB.
- Does it record what I say?
- No. The app reads the level and throws the audio away. Noise logs keep only numbers, once a second. There is no account and nothing is uploaded.
- What is A-weighting?
- Your ears are less sensitive to very low and very high sounds. A-weighting adjusts the reading the same way, so it matches how loud something feels. Hearing limits from NIOSH and OSHA are given in A-weighted decibels (dBA). C-weighting keeps more of the bass and is useful for music.
- Is it free?
- The live meter, the tone generator and the speaker cleaner are free, and your first 3 noise logs are free. Pro adds unlimited logs, PDF reports, C and Z weighting, calibration and the 20 Hz–20 kHz sweep: $19.99 once, $9.99 a year, or $1.99 a week.