6 surprising things you can measure with your Android phone
Our smartphones are often smarter than we give them credit for. They are full of sensors capable of measuring all sorts of things. You’re probably familiar with the most common ones, like steps and elevation, and before smartwatches became common, there was even a brief period when some phones included heart rate sensors.
But that’s not what I’m here to talk about today. There are some truly fascinating, if not downright bizarre, things that a phone can measure, which usually require specialized or expensive tools. Still, with nothing more than its built-in sensors, your phone can sometimes get the job done. Here are some of the coolest things your smartphone can do.
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Check the volume of something or someone
One of the simplest tools on this list might also be one of the most useful. A sound level meter app uses your phone’s microphone to measure sound levels in decibels.
Whether you’re concerned about the noise level in your surroundings, want to check the sound level of your speakers to protect your hearing, or simply want to settle an argument with a particularly noisy co-worker, this app lets you see how loud things really are.
The important thing to keep in mind is that your phone’s microphone is probably located at the bottom, so you can get very different readings depending on how you hold it. Since your ears are best at picking up sound coming directly in front of you, tilt your phone so that the bottom faces the sound source.
Also remember that sound levels decrease with distance. Do not place your phone directly in front of the source, such as a speaker. Measure at your actual listening position for the most accurate results.
Measuring magnetic field strength
Many phones come with a built-in compass app, and even if they don’t, you can download a third-party app to use your phone as a digital compass.
This works because smartphones contain a magnetometer that detects the Earth’s magnetic field. Map apps like Google Maps and Apple Maps often combine the magnetometer with the gyroscope and accelerometer to determine the direction your phone is facing.
But did you know that the same magnetometer that powers the compass can also measure the strength of a magnetic field?
And no, I’m not just talking about the Earth’s magnetic field (although that too); I mean pretty much any magnet or magnetic device. For example, I brought a small neodymium magnet closer to my phone and observed a sudden spike in µT (microtesla).
You can use this type of app to measure variations in the Earth’s magnetic field for entertainment or educational purposes, locate hidden magnetic objects, identify sources of magnetic interference (like understanding why your phone’s magnetometer works), detect metallic objects, and much more.
Measuring light levels from artificial and natural sources
Ever wanted to measure the amount of light emitted by a device, like a flashlight or monitor?
A light meter app does just that. It cleverly uses the ambient light sensor inside your phone (the same one responsible for automatic brightness adjustment) to measure the amount of light hitting the sensor.
This is a handy tool if you want to check the amount of light reaching a certain area. For example, you can measure the light your houseplants receive during part of the day or the strength of an artificial source.
You don’t really need an expensive lux meter, especially if you’re just looking for an approximate lux range rather than a precise measurement.
Measure air pressure to help predict the weather
A barometer is a tool that measures atmospheric pressure, and surprisingly, many phones have built-in barometers that can display the current pressure with good accuracy.
You can use this information to predict short-term weather changes in your exact area, which may differ from what your weather widget displays. This can be helpful information if you experience weather-related pain.
You can also use it to estimate your altitude while hiking, because air pressure changes with altitude.
Measuring the pitch of a musical instrument
Before purchasing a chromatic tuner pedal for my guitar and bass, I used the Guitar Tuna app on my phone and had great success tuning my instruments.
Tuner apps use your phone’s microphone to record sound and then estimate how close your string’s pitch is to the target note.
What surprised me the most was how accurate these apps were. From what I can tell, some of them are just as accurate, if not more so, than my cheap Behringer pedal.
Checking the accuracy of a mechanical watch
Here’s another app that uses the microphone, but instead of measuring the pitch of a guitar string, this one listens to the ticks of an automatic or hand-wound mechanical watch and provides an estimated measurement of beat frequency, beat error, and amplitude. It’s basically a poor man’s chronograph.
You can use this information to fine-tune the accuracy of your watch using the small regulator located above the balance wheel.
When I first tried the Watch Accuracy Meter app on Android, I honestly thought it might be a gimmick. However, I was surprised by its accuracy.
Using only the app, a toothpick, and a little patience, I was able to restore two vintage Seikos without an expensive visit to a watch repair service.
I adjusted my watch until the beat rate was a few seconds per day, then used another app to track its accuracy over several days. My Seiko 5 now only gains about 9.6 seconds per day.
This is an impressive result for any mechanical watch, especially an antique watch that hasn’t been serviced in decades.
While your phone isn’t much of a replacement for a dedicated measuring tool, it can still do a surprisingly solid job when you need quick, convenient measurements. More often than not, the accuracy will be more than adequate for the project you’re working on, which is great when the actual tool costs three figures.
