Land Measurement App: What to Look For and How to Test One
A land measurement app turns your phone's GPS and a satellite map into area, perimeter and distance figures. A good one lets you both tap corners on the map and walk the boundary, keeps working without a signal, and exports your fields in a format you can use. Before you trust any app with a real decision, test it on a plot whose size you already know.
That test takes about 10 minutes and tells you more than a feature list, so this guide covers both: what to check, and how to check it.
What a field measurement app actually does
Nearly every app in this category does the same core job. It collects a series of points, joins them into a closed shape, and calculates the area from their coordinates. The points reach the app in one of two ways:
- Tapping on a satellite map. You place each corner by eye. Accuracy depends on how clearly the edge shows in the imagery and how carefully you place the points.
- Tracking with GPS. You walk, drive or fly the boundary and the app records your path. Accuracy depends on the phone's GPS signal and on how close to the true edge you can get.
No app can get more out of the phone's GPS than the phone provides. Under open sky that's typically about 3–5 m, and worse under trees or near buildings. What differs between apps is how easy they make it to work around those limits, and what you can do with a field once it's measured.
What to look for in a land measuring app
| Feature | Why it matters |
|---|---|
| Both map tapping and GPS tracking | Tapping suits plots with visible edges. Walking suits edges you can't see from above. |
| A magnifier for placing points | Your finger hides the corner you're aiming at. On a small plot a few metres changes the result. |
| Offline measuring | Signal is often weakest at the far end of the farm, right where you need it. |
| Your units | You need the figure in the unit you buy, sell and spray by, or a clear number you can convert. |
| Saved, named fields | You'll want to compare a field next season, not measure it again. |
| Export formats | CSV suits a spreadsheet. Shapefile, KML or GeoJSON suit GIS software and farm systems. |
| Shared workspaces | Useful if a team, an agronomist or a contractor needs the same field boundaries. |
| Device support | Check that it runs on your phone before planning around it. |
Decide which of these you need first. If you measure one plot a year, tapping and a saved result are enough. If you hand boundaries to a contractor, export comes first.
How to test any app on a known plot
Don't judge an app on a field whose size you're trying to find out. Use one whose size you already know.
- Find a known shape. Tape out a rectangle yourself, or use a plot with dimensions you trust. Choose open ground, away from trees and walls.
- Tap the corners on the satellite map and note the area and perimeter.
- Walk the boundary with GPS tracking, finishing where you started, and note the same two numbers.
- Walk it again in the opposite direction. The gap between the two walks shows how much noise to expect.
- Turn on airplane mode and repeat one short track. GPS itself doesn't need a data connection. You'll find out if the app does.
- Save the field and export it. Open the file in whatever you'll actually use. It's better to discover a problem now than at planting time.
Worked example: reading your test results
Say you tape out a rectangle of 100 × 50 m. The true area is 5,000 m² (0.5 ha, 1.24 acres) and the perimeter is 300 m. You walk it twice and get:
- First walk: 5,120 m², which is 2.4% over
- Second walk: 4,930 m², which is 1.4% under
The two walks differ by 190 m², or 3.8% of the true area. Is that good enough? It depends on the job. At 200 kg of fertiliser per hectare, this plot needs 100 kg, and a 2.4% error comes to 2.4 kg. For planning inputs that's fine. For settling a boundary with a neighbour, no phone is good enough.
How accuracy changes with field size
The same GPS error matters much more on a small plot, because the error scales with the perimeter while the area grows much faster. This table shows the extreme case, where every side is off by 3 m in the same direction:
| True field | All sides 3 m inward | All sides 3 m outward |
|---|---|---|
| 40 × 25 m (0.1 ha) | 646 m² (−35.4%) | 1,426 m² (+42.6%) |
| 100 × 50 m (0.5 ha) | 4,136 m² (−17.3%) | 5,936 m² (+18.7%) |
| 200 × 100 m (2 ha) | 18,236 m² (−8.8%) | 21,836 m² (+9.2%) |
| 500 × 200 m (10 ha) | 95,836 m² (−4.2%) | 104,236 m² (+4.2%) |
Real errors rarely all point the same way, so results are usually much closer than this. The pattern still holds: for a tenth of a hectare, use a tape or a very careful map outline. For ten hectares, a phone is comfortable. How to measure land area by walking has more on keeping the error down in the field.
Measuring with Field Maps with Area Measure
Field Maps with Area Measure is built around the two methods above: tap points on a satellite map, with a magnifier loupe for precise corners, or walk, drive or fly the boundary and let it close the shape. It shows area, perimeter and distance in m², hectares, km², square feet, square yards, acres or square miles, using geodesic math on the WGS-84 ellipsoid. You can search an address or centre on your location, and save each field with a name.
GPS tracking and measuring work offline. A brand-new map area needs a connection to load its imagery, and areas you've already cached stay available. It runs on iPhone and iPad (iOS 17 or later), and there's no Android version yet.
What's free and what's in Pro
The free version covers measuring area, perimeter and distance, saving fields, CSV and plain-text export, a map image and a shareable web link. You can also create and join workspaces, and sign-in is optional.
Pro is a subscription. It adds Shapefile, DXF, KML, KMZ, GeoJSON and GPX export, PDF field reports, and splitting a field into sections. It also lets you edit as an editor in someone else's workspace.
If you'd like to compare methods before installing anything, measuring by satellite or GPS walks through both techniques in general.
FAQ
Is there a free land measurement app?
Yes. Field Maps with Area Measure measures area, perimeter and distance for free, and lets you save fields and export them as CSV or plain text. The GIS export formats and PDF reports are part of Pro.
Does a land measuring app work without internet?
GPS doesn't need a data connection, so tracking and measuring can work offline. Satellite imagery is different: a map area has to be loaded once before you can see it without a signal. Check this before you head out to a remote field.
Is this app available on Android?
Not yet. Field Maps with Area Measure is for iPhone and iPad only. A Google Play waitlist exists for an Android version.
Can I use an app's measurement for a land sale or a legal dispute?
No. A phone measurement is an estimate, useful for planning and for checking that a figure looks right. For a sale, a dispute or anything legal, use a licensed surveyor and the official land records.