Comparison

CrowdMag vs Linear Interpolation Master

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

CrowdMag

This app allows users to measure and contribute to scientific research on Earth's magnetic field using their smartphone. It offers features for recording magnetic data during various activities, including flights, and provides tools for data visualization and analysis.

Highlights
  • Measure magnetic field data
  • Contribute to scientific research
  • Record data during flights
  • Visualize data on maps and graphs
  • Magnetic calculator with WMM2020
  • Live magnetic compass
  • Export data via email/Google Drive
Features
Read full description

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://geomag.colorado.edu/crowdmag-flight-mode-tutorial . 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://geomag.colorado.edu/crowdmag to see crowdsourced magnetic data .

About

Linear Interpolation Master

This tool simplifies linear interpolation calculations for industrial commissioning engineers. It features large, easily readable numbers for field use and allows for quick swapping of coordinate systems, such as converting between 4-20mA and 0-100% scales.

Highlights
  • Large number display for field visibility
  • Quickly swap X and Y coordinates
  • 4-20mA to 0-100% conversion
  • 0-100% to 4-20mA conversion
Features
Read full description

A linear interpolation calculator designed for industrial commissioning engineers. It has the following features: - Displays large numbers for when you are out in the field commissioning. - Allows quickly swapping x and y coordinates; for example from 4-20mA -> 0-100% to 0-100% -> 4-20mA.

Screenshots

CrowdMag4 screens
Linear Interpolation Master3 screens

Verdict

The call

The clearest difference is in-app purchases: CrowdMag at none against Linear Interpolation Master's 3. CrowdMag also leads on ads (none vs shown) and update cadence (every 2 months vs every 5 months). Linear Interpolation Master's advantage is rating (4.7 vs 4.3) and ratings volume (176 vs 24). On price and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Linear Interpolation Master sells 3 one-off in-app purchases. CrowdMag asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Linear Interpolation Master holds the better App Store score, 4.7 against 4.3. That said, the two scores are not equally well evidenced: Linear Interpolation Master has 176 ratings behind it against 24, so its average is the more settled of the two. Written reviews point the same way: 53% of CrowdMag's written reviews are positive against 63% of Linear Interpolation Master's.

UpkeepUpdate frequency

CrowdMag ships an update every 2 months, Linear Interpolation Master every 5 months. Both last shipped on September 22, 2026.

Scorecard8 real differences · 2 level
CrowdMag versus Linear Interpolation Master: the parameters behind the verdict, then further details
ParameterCrowdMagLinear Interpolation Master
PriceFreeFree
Rating4.3 (24 ratings)4.7 (176 ratings) — better
Positive reviews52.9% of reviews62.5% of reviews — better
Number of ratings24176 — better
Update frequencyEvery 2 months — betterEvery 5 months
AdsNo — betterYes
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.011.0 — better
Further details — not scored
Size18 MB16 MB
Age rating4+4+
DeveloperUniversity of Colorado BoulderVERVE TECHNOLOGIES PTY. LTD.

Customer experience

CrowdMag

All ratings24 ratings
Positive79.2%
Neutral8.3%
Negative12.5%
Written reviews17 reviews
Positive52.9%
Neutral17.6%
Negative29.4%

Linear Interpolation Master

All ratings176 ratings
Positive92.6%
Neutral2.8%
Negative4.5%
Written reviews8 reviews
Positive62.5%
Neutral25.0%
Negative12.5%

In-app purchases

None

CrowdMag

No in-app purchases

3 purchases

Linear Interpolation Master

One-time3
  • Generous Tip$2.99
  • Massive Tip$3.99
  • Amazing Tip$4.99

Questions

Is CrowdMag free?
CrowdMag is free to download, with no in-app purchases.
Is Linear Interpolation Master free?
Linear Interpolation Master is free to download, with in-app purchases available.
Which has better reviews, CrowdMag or Linear Interpolation Master?
Linear Interpolation Master is rated higher. CrowdMag averages 4.3 out of 5 from 24 ratings, while Linear Interpolation Master averages 4.7 from 176 ratings.
Do CrowdMag or Linear Interpolation Master have ads?
Linear Interpolation Master shows ads; CrowdMag does not.
Which is updated more often, CrowdMag or Linear Interpolation Master?
CrowdMag ships an update every 2 months, and Linear Interpolation Master every 5 months. Most recently, CrowdMag was updated on September 22, 2026 and Linear Interpolation Master on September 22, 2026.

Other comparisons