There are countless reasons why one might want to know one’s current elevation in comparison with the sea level. Farmers rely on this information to set up gravity-fed irrigation systems, people with high altitude illnesses and sensitivities use it to determine whether they’re facing any potential risks, and hikers see it as a fun way how to make their adventures even more interesting.
The good news is that you can find out your elevation with just your iPhone and one of the altitude apps described in this article. Even though they don’t reach the level of accuracy of professional pressure altimeters or barometric altimeters, they’re accurate enough to satisfy the needs of most people.
How Does the iPhone Measure Elevation?
Older iPhones relied solely on GPS for altitude calculation. The GPS technology is based on a process known as triangulation, which makes it possible to very accurately measure exact position anywhere on earth by measuring the distance from three satellites and applying some clever technical tricks to reject ridiculous readings. Four satellites are needed to mathematically determine exact position, and the more satellites your iPhone is connected to, the faster it will deliver reliable readings.
Since the release of the iPhone 6 and 6 Plus, elevation can be calculated using air pressure readings provided by a built-in barometer sensor. As demonstrated by iFixit and their teardown of the iPhone 7, this sensor is located behind the left speaker grille. It was initially assumed that the left grille is there only for aesthetic purposes, but, according to Apple, it’s actually a barometric vent. The vent was added to make the barometer functional and accurate despite all the waterproofing done to the iPhone 7. The main advantage of a barometer sensor over GPS is its superior power efficiency.
With its beautifully designed user interface, Travel Altimeter Lite elegantly combines form with function. Altitude, latitude, and longitude are all displayed together on top of a fully customizable background. The app also provides a convenient shortcut to a built-in flashlight and a variety of sharing options. If you’re willing to spend just a few dollars, you can get even more out of the app by purchasing extra features, stunning backgrounds, and by removing advertisements.
Elegant, packed with useful features, and fully functional even without an internet connection—that’s My Altitude in a nutshell. The app can measure altitude in two different ways. By default, it uses your iPhone’s sensor, but you can also manually download data from the National Oceanic and Atmospheric Administration for offline use. One nice extra feature is the ability to take a picture of where you are and save it in photo album. My Altitude will automatically pair the picture with the coordinates of your current location.
The Barometer & Altimeter for iPhone/iPad is designed to simulate the look and feel of analog barometers and altimeters. It works only with newer iOS devices equipped with a barometric pressure sensor. This includes the iPhone 6, 6s, 7, 7 Plus, iPad Air 2, Mini 4, and iPad Pro. The free version comes with all important features, such as up to 30-day trend visualizations, interactive timeline, and graphs, support for manual altitude setting and automatic updates. The Pro version, which costs $1.99, adds a fishing barometer, two scales on the default barometer, and the ability to export data in CSV format.