Last updated: March 2026
What Is the Online Decibel Meter?
The Online Decibel Meter is a free tool that measures ambient sound levels using your device's microphone — no signup, no app download required. See real-time decibel readings on a visual gauge with color-coded zones for safe, moderate, loud, and dangerous sound levels.
Prolonged exposure to sounds above 85 dB can cause permanent hearing damage, according to the CDC's National Institute for Occupational Safety and Health. An estimated 40 million US adults show signs of noise-induced hearing loss. Professional sound level meters cost $30-200, but this browser-based tool gives you instant approximate readings for free.
The meter displays current, average, peak, and minimum levels with a scrolling history graph. It includes a reference chart of common sounds (whisper at 20 dB to jet engine at 130 dB) and supports A-weighting for human-hearing-adjusted measurements. All processing happens locally — audio is never recorded or uploaded.
How to Use the Online Decibel Meter
Step 1: Click "Start Measuring" and allow microphone access when your browser asks.
Step 2: The gauge immediately shows the current sound level in your environment.
Step 3: Move around your space to measure different noise levels — the gauge updates in real time.
Step 4: Check the reference chart to understand what your reading means (conversation, traffic, concert levels).
Step 5: Use the calibration slider if you have a reference meter to adjust for your microphone's sensitivity.
Step 6: Export readings as CSV for documentation, or note the peak level for noise assessments.
Key Features
Visual semicircular gauge. A speedometer-style SVG gauge with a smooth animated needle and six color-coded zones from quiet green to pain-threshold dark red. Current reading is displayed large in the center.
Peak, average, and min tracking. Monitor your sound environment over time. The peak value catches loud transients you might miss, while the average gives you a reliable exposure estimate.
Scrolling history graph. A 60-second scrolling chart shows how sound levels change over time. Useful for identifying noise patterns, intermittent sounds, or tracking improvements after soundproofing.
A/C/Z frequency weighting. Switch between dBA (human hearing adjusted, recommended), dBC (flat, for peak measurements), and dBZ (unweighted raw). dBA is the standard used in noise regulations worldwide.
Reference chart with live indicator. Compare your current reading against common sounds from a 20 dB whisper to a 130 dB jet engine. Your current level is highlighted in real time.
CSV export. Download the last 60 seconds of readings as a timestamped CSV file for documentation, reports, or further analysis.
Frequently Asked Questions
How accurate is an online decibel meter?
Browser-based meters measure relative digital audio levels (dBFS), not absolute SPL. Accuracy depends on your microphone quality. Results are useful for comparing sound levels and general monitoring but aren't suitable for legal compliance or occupational safety — use a calibrated SPL meter for those.
What decibel level is dangerous for hearing?
Sustained exposure above 85 dB can cause hearing damage. At 100 dB (power tools, concerts), damage can occur within 15 minutes. At 120 dB (sirens, jet engines), pain and immediate damage are possible.
Can I use my phone as a decibel meter?
Yes — this tool works on iPhone (Safari) and Android (Chrome). Phone microphones are decent for approximate readings. For best accuracy, keep the phone mic pointed toward the sound source without covering it.
What is A-weighting (dBA)?
A-weighting adjusts the reading to match how human ears actually perceive loudness. We're less sensitive to very low and very high frequencies. dBA is the standard for noise regulations and hearing safety measurements.
What is a normal indoor noise level?
A quiet home measures around 30-40 dB. Normal conversation is 60-70 dB. An office environment is typically 45-65 dB. If your indoor reading consistently exceeds 70 dB, that's above the recommended background level.