Measure sound levels
with precision.

Loudly is a professional-grade decibel meter app for iPhone. It measures ambient sound levels in real time, categorizes noise into 7 levels from Quiet to Extreme, and supports IEC 61672 compliant frequency weightings. No subscriptions, no accounts, no data collection.

Loudly uses IEC 61672 compliant signal processing with professional-grade frequency weighting filters. While iPhone microphones are consumer-grade, Loudly includes a calibration feature (Pro) to adjust readings against a known reference. For casual use and awareness, it's highly reliable. For legal or occupational compliance, use certified professional equipment.

Frequency weightings filter sound to match how we perceive loudness at different frequencies. A-weighting (dBA) is the most common standard, mimicking human hearing. C-weighting (dBC) is flatter and better for loud, low-frequency sounds like music or machinery. Linear/Z-weighting (dBZ) applies no filtering and shows raw sound pressure levels.

Loudly categorizes sound into: Quiet (under 40 dB), Moderate (40–60 dB), Loud (60–70 dB), Very Loud (70–80 dB), Dangerous (80–90 dB), Very Dangerous (90–100 dB), and Extreme (above 100 dB). Each category includes health guidance and safe exposure time information.

No. Loudly processes microphone input in real time to calculate decibel levels, but never records, stores, or transmits any audio. The raw audio data is discarded immediately after the dB calculation. We cannot hear what's happening around you.

IEC 61672 is the international standard for sound level meters, published by the International Electrotechnical Commission. It defines specifications for frequency weighting filters (A, C, Z) and time weightings (Fast, Slow, Impulse). Loudly follows this standard for its signal processing algorithms.

Loudly Pro costs $2.99 as a one-time purchase. There are no subscriptions, no recurring fees, and no ads. The core decibel meter is free forever — Pro unlocks advanced features like additional weightings, calibration, and measurement history.

Yes, with Loudly Pro. The calibration feature lets you adjust the dB offset to match a known reference source or professional meter. This compensates for microphone variations between iPhone models and improves measurement accuracy.

Loudly collects zero personal data. There are no analytics, no tracking SDKs, no accounts, and no servers. Your measurement history is stored locally on your device only. Audio is processed on-device in real time and never recorded or transmitted.

Loudly Pro is tied to your Apple ID. On a new device or after reinstalling, open the Pro upgrade screen and tap "Restore Purchases." Make sure you're signed in with the same Apple ID you used for the original purchase. You won't be charged again.