Tools & Utilities
Measure Decibels
Know exactly how loud your world is.
Measure Decibels turns your iPhone into a professional-grade sound level meter (SPL meter). Measure noise levels in real time, track peaks, and know when your environment is too loud for safe hearing.
Download Free on App StoreWhat it does
Everything you need,
nothing you don't.
Real-Time SPL Meter
Measures sound pressure levels in decibels (dB) using your iPhone microphone.
Peak Level Tracking
Captures the loudest point in any session so you don't miss spikes.
Hearing Safety Guidance
Colour-coded levels indicate when noise is safe, caution-level, or dangerous for hearing.
Clean, Readable Display
Large, easy-to-read display so you can check levels at a glance.
In depth
Everything about
Measure Decibels.
Decibel Meter
A decibel meter measures sound pressure level (SPL) in dB — a logarithmic scale where 70 dB is 10 times louder than 60 dB, not just slightly louder — and is used in occupational health, environmental monitoring, acoustic research, and personal hearing protection. Measure Decibels turns your iPhone into a portable SPL meter, applying A-weighting (the industry standard for human hearing assessment) to deliver real-time readings comparable to dedicated hardware, with no extra accessories required. The app displays current, peak, and average levels alongside color-coded safety zones, and flags thresholds based on NIOSH and OSHA guidelines so you can immediately judge whether prolonged exposure poses a risk. Session logging lets you review peak moments after the fact, making it equally useful for quick spot checks in offices or restaurants and longer monitoring sessions in construction or workplace settings.
Sound Exposure Level
Sound exposure level (SEL) accounts for both the intensity and the duration of a noise event, making it a more complete measure of hearing risk than a single dB reading. Measure Decibels tracks real-time SPL and displays cumulative exposure guidance so you understand not just how loud it is now but how long you can safely remain in the environment. This is particularly useful at concerts, construction sites, or any prolonged noisy activity.
Handheld Decibel Meter
Dedicated handheld SPL meters — used by acousticians, safety officers, and venue managers to assess ambient noise in workplaces, events, and public spaces — can cost $50–$500 depending on accuracy class. Measure Decibels replicates the core functionality of this hardware on your iPhone: real-time SPL readings, peak hold, A-weighting, and hearing safety indicators that update continuously as you move through different environments. For most non-regulatory applications, the app provides sufficient accuracy without the cost or bulk of a separate device — and because it runs on hardware you already carry, there's nothing extra to purchase or maintain.
Decibel Meter App
Your smartphone's microphone continuously samples audio, calculates the root mean square of the pressure wave, and maps it to the dB SPL scale — a range spanning from 0 dB (threshold of hearing) to roughly 140 dB, with most iPhone microphones reliably covering 30–120 dB. Key metrics to watch are the current level, peak level, and time-averaged (Leq) exposure, since a single loud spike and sustained high-volume noise carry different risks. Measure Decibels tracks all three in real time, displays safety-band indicators, and labels readings with plain-language context — quiet, moderate, loud, or potentially harmful — so you can act on the numbers without needing an acoustics background. Accuracy depends on microphone quality and placement, making the app a practical everyday guide for checking restaurant noise, evaluating hearing protection needs, or monitoring your environment, rather than a substitute for certified measurement equipment.
Noise Meter for Classroom
Research consistently shows that classroom noise above 35–40 dB harms student concentration and strains teacher vocal health, making real-time sound monitoring a practical classroom tool. Measure Decibels runs on any iPhone or iPad — no dedicated hardware needed — displaying a large, color-coded dB readout that teachers and nearby students can glance at during lessons. Placed on a desk or mounted at the front of the room, it acts as a passive visual cue that reinforces quiet expectations without constant verbal reminders, and lets teachers or administrators intervene before noise reaches disruptive levels.
Common questions
Questions answered.
Everything you need to know about Measure Decibels.
How loud is 50 decibels?
50 decibels is about the level of a quiet office or light rainfall. It's generally considered a comfortable, low-noise environment and poses no risk to hearing.
How loud is 60 decibels?
60 decibels is roughly the volume of normal conversation or a restaurant at moderate activity. It's well within safe hearing limits for extended exposure.
How loud is 85 decibels?
85 decibels is the threshold at which prolonged exposure begins to risk hearing damage — equivalent to heavy city traffic or a loud lawn mower. NIOSH recommends limiting unprotected exposure to 8 hours at this level.
How loud is 120 decibels?
120 decibels is extremely loud — comparable to a jet engine at close range or a live rock concert near the speakers. Exposure even for a few seconds can cause immediate hearing damage.
How loud is 70 decibels?
70 decibels is similar to a vacuum cleaner or busy street traffic. It's generally safe for extended periods but can become fatiguing over many hours.
How loud is 80 decibels?
80 decibels is roughly the volume of a garbage disposal or a noisy restaurant. Regular exposure above 80 dB over long periods can contribute to gradual hearing loss.
How loud is 90 decibels?
90 decibels is comparable to a motorcycle or power tools. NIOSH recommends no more than 2 hours of unprotected exposure per day at this level.
How to measure decibels?
Decibels are measured using a sound level meter, which uses a microphone to capture sound pressure and converts it to a dB reading. On iPhone, apps like Measure Decibels use the built-in microphone to provide real-time SPL readings without any extra hardware.
How to measure sound decibels?
Point your iPhone's microphone toward the sound source and open a decibel meter app to get an instant reading. For best accuracy, hold the phone steady and avoid covering the microphone.
How many decibels is too loud?
Sounds above 85 dB are considered hazardous with prolonged exposure, and anything above 120 dB can cause immediate damage. The World Health Organization recommends keeping recreational noise below 70 dB averaged over 24 hours.
How do you measure decibels?
Professional-grade sound level meters use calibrated microphones and weighted filters (typically A-weighting) to measure how loud a sound is in decibels. Smartphone apps approximate this using the device's built-in microphone and are accurate enough for everyday noise monitoring.
How to test decibels?
Open a decibel meter app on your iPhone and hold it in the environment you want to test. The app displays a real-time dB reading, and most also track peak levels so you can see the loudest moment during the measurement period.
How can i measure decibels?
You can measure decibels with a dedicated SPL meter device or with a smartphone app that uses the built-in microphone. iPhone apps are a convenient option for quick noise checks at work, home, or events.
How loud is 40 decibels?
40 decibels is very quiet — similar to a library or a whispered conversation. Most people find environments at this level peaceful and ideal for sleep or concentration.
How to measure db?
dB (decibels) are measured by capturing the sound pressure level at a microphone and applying a logarithmic scale. On iPhone, open a sound level meter app and the microphone does this automatically, displaying the result in real time.
How do i measure decibels?
Install a decibel meter app on your iPhone, open it, and hold the phone near the sound source. The app reads the microphone input and shows the current noise level in dB, along with peak values.
How can you measure decibels?
Decibels can be measured with a standalone SPL meter or a smartphone app. A phone-based meter is accurate enough for everyday use — checking a noisy workplace, a concert, or your home environment.
How loud is 55 decibels?
55 decibels is about the level of a moderate rainfall or a quiet suburban street. It falls within the range most people describe as background noise and is safe for unlimited exposure.
How to measure a decibel?
A decibel is measured by comparing a sound's pressure level to a standard reference using a logarithmic formula. In practice, a sound level meter or smartphone app handles the calculation and displays the result instantly.
How to measure sound db?
Open a sound level meter app on your iPhone and allow it to access the microphone. The app continuously reads incoming sound and displays the level in dB, often with a graph of how it changes over time.
Is Measure Decibels free?
Measure Decibels is available on the App Store with a free version that covers core sound level metering. Some advanced features such as data logging or export may require an in-app purchase or a one-time upgrade.
Does Measure Decibels work offline?
Yes, the app works entirely offline — sound measurement relies only on your iPhone's microphone and the app's on-device processing. No internet connection is needed to take readings.
What iOS version does Measure Decibels require?
Measure Decibels requires a recent version of iOS and is optimized for current iPhone models with Apple's latest microphone hardware. Check the App Store listing for the minimum iOS version supported.
How accurate is Measure Decibels?
iPhone microphones are optimized for voice, not precision acoustics, so readings are typically within ±2–3 dB of a calibrated meter under normal conditions. For general noise monitoring, workplace checks, or hearing safety awareness, that accuracy is sufficient — professional industrial hygiene work still requires a certified SPL meter.
Does Measure Decibels store or share my audio?
The app processes microphone input in real time on your device and does not record or transmit raw audio. Only numeric dB readings are used, and no audio files leave your iPhone.