441 reviews
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About this app

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: https://www.noaa.gov/education/resource-collections/data/tiny-tutorials/crowdmag-flight-mode.

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 https://www.ncei.noaa.gov/products/crowdmag-magnetic-data to see crowdsourced magnetic data.
Updated on
Apr 12, 2024

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
No data shared with third parties
Learn more about how developers declare sharing
This app may collect these data types
Data is encrypted in transit
Data can’t be deleted

Ratings and reviews

417 reviews
Jacob Bingham (UFTS)
February 14, 2024
I wish this wasn't buried in the search results among thousands of garbage compass apps, this app (which is literally from NOAA themselves) is a compass, allows you to calculate magnetic declination and true north, calculate changes in the magnetic field using a model, crowd source (log and contribute) to a magnetic field model, and more. It uses old Android UI elements, but still receives updates (most recent one added a 1 Hz log rate option) so I will not complain.
6 people found this review helpful
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NOAA's National Geophysical Data Center
February 20, 2024
Thank you so much for your feedback.
Anton G
May 5, 2024
Very useful to get magnetic declination for anywhere on your phone. Unfortunately last update introduced a bug: WMM and EMAG overlays just show to the west from Greenwich meriduan, with eastern hemisphere data overlaid over the western one in a mirrored way. As if the right half of the map were folded over the left one and left there. It was not this way before. Edit: bumped up to 4 stars after a promise of a fix. Edit2: fixed, and 5 stars
2 people found this review helpful
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NOAA's National Geophysical Data Center
March 29, 2024
Thanks for bringing this to our attention there was an update in the google maps API which caused this bug. This will be fixed in the next update.
Brian Burns
May 8, 2020
I like the idea behind this app, unfortunately on all three of my phones it"s a bit flaky. On the Wileyfox Swift it requires a compass recalibration every couple of minutes, on the Samsung I-9100 it just crashes and hangs the phone, on the Galaxy Mini 2 it"s just generally unstable. A cut down version of this software which just uploads the data to your server for older phones would be nice, as I could then use one of the older "retired" phones I have as a dedicated fixed location sensor.
5 people found this review helpful
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What's new

* Introducing an attractive new web map for contributed data.
* Added Paperwork Reduction Act Burden Statement.