CrowdMag 4+

National Oceanic and Atmospheric Administration

Designed for iPad

    • 4.1 • 19 Ratings
    • Free



Introducing CrowdMag's newest feature: Flight Mode, which lets you contribute to scientific research by measuring the magnetic field as you fly around the world. To get started, simply provide your itinerary on the CrowdMag app, and you'll be able to turn your flight into a scientific expedition. Check out this step-by-step tutorial for measuring data while flying: .

CrowdMag is an app that lets you measure the local magnetic field using your smartphone. You can view the data as a graph or a map in nanotesla units. CrowdMag measures the Z (downward component), H (horizontal intensity), and F (total intensity) magnetic field components. You can use CrowdMag for measuring magnetic data during outdoor activities, while flying, or to conduct your own experiments. You can also share it with NOAA to help scientists better understand Earth's magnetic field.

If you're going for a walk, run, or other outdoor activities, you can use CrowdMag to measure the magnetic data along your path and save it as a "magtivity." And, if you get a new phone, don't worry! You can export a backup of your CrowdMag data and save it on your computer. This way, if you have to reset your phone or switch to a new one, you can import your backup and continue using CrowdMag without losing your data or progress.

CrowdMag also has a magnetic calculator that provides magvar (declination), the magnetic field's dip angle, total magnetic field, and other magnetic field components based on the latest World Magnetic Model (WMM2020). Some of the other features of CrowdMag include creating your own magtivities, customizing recording frequency and location accuracy, exporting your data via email or Google Drive, and seeing generalized crowdsourced magnetic data from other users.

And, before we forget, CrowdMag also features a compass that distinctly shows both true and magnetic north. As an added feature, the compass also has a 3D display with an optional audio output - check it out!

CrowdMag features:

* Create your own magnetic activity (called a "magtivity")
* Measure data while flying
* Customize recording frequency and location accuracy to your preferences
* View your magnetic data on an interactive Google Map
* Graph your data as a time series line chart
* Check the quality of your data by comparing it with the World Magnetic Model (WMM)
* Export your data as a CSV file
* Clear stored data on your phone when you want to start fresh
* Choose to share your data with NOAA (optional)
* See generalized crowdsourced magnetic data from other users
* Use the live magnetic compass for 2D and 3D rendering
* View information about the current solar magnetic disturbance
* Use the most up-to-date magnetic field model (WMM2020)
* Export your data via email, Google Drive, or other options
* Export a CrowdMag backup to save your contributions' status and data
* Import your CrowdMag backup (works across different phone platforms)

Visit to see crowdsourced magnetic data .

What’s New

Version 2.0.7

Updated the compass tab and added haptic feedback.

Ratings and Reviews

4.1 out of 5
19 Ratings

19 Ratings

Jason somthing ,

Zero effort to contribute to cool research

Just open the app and set how often you want to send them data. These types of apps are a great way to harness the power of your iPhone and with no effort make a positive contribution. Nice touch adding achievements for contributions and locations. The magnetic information is interesting to see but that’s about it. Just know your contribution will help other researchers.

KB Traveler ,

Excellent Info

I travel the world for a living. Knowing the correct Mag Variation has come in handy. The latest version includes an excellent compass which gives both True and Magnetic North. It is nice to be able to contribute information for this program. I find that it doesn't effect my battery usage that much.

Adam Woodworth ,


I am a photographer and I use this app to find the magnetic declination of my current location so that I can correct my compass readings to true north to match with the true north bearings given in some landscape photography planning apps.

App Privacy

The developer, National Oceanic and Atmospheric Administration, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Location

Privacy practices may vary, for example, based on the features you use or your age. Learn More

More By This Developer


You Might Also Like