How to measure a field: decare, perimeter, boundary and KML
Field measurement often starts with one question: how many decares is this land?
Field takeaways
- Field area needs a closed polygon.
- 1 decare equals 1000 square metres.
- Phone GPS is approximate.
- Parcel KML can be reference; walking track can record occupation.
- MapLab Survey combines area, perimeter, notes and exports.
Decide which boundary you are measuring
The parcel line, the fence, the cultivated area and the section to be irrigated can be four different lines on the same field. Pick one before measuring and write the boundary source next to the result; "the field is 11.8 decares" is incomplete until it says which line it belongs to.
Walking versus drawing
Walking the boundary captures the real shape, including the awkward corners and fence turns. Drawing a polygon on imagery is faster and cleaner, but it inherits any shift or age in the image. For planning, drawing is usually enough; to know what is on the ground, walk it.
The workflow in MapLab Survey
Open a project and create a field-measurement layer. Record the boundary by walking or draw the polygon on the map; close it and read area and perimeter together. Add photos and notes at the important corners, then share the result as KML, DXF or a report with the coordinate system noted, so the figure can be verified later.
Corners, not steps
When walking, stop and record a point at each corner and let the straight sections run between them. Continuous tracking writes every step's GPS noise into the polygon, and that noise inflates both area and perimeter. Return to the first corner and confirm the polygon actually closes.
Decares and the accuracy to expect
Area reads in square metres; divide by 1,000 for decares — 12,400 m² makes 12.4 decares. A rough planting figure, a subsidy application and a sale negotiation demand three different levels of accuracy: phone GPS works at metre level, and where centimetres matter an external RTK receiver joins the same workflow.
Do not confuse it with the registered area
A phone-measured area serves planning, reconnaissance, fencing cost and irrigation calculations. For a deed, a sale, a dispute or any official procedure, the cadastral record and an authorised survey govern — that is licensed surveying work. The app speeds up the field half of that job; it does not replace the signature half.
Try these steps on your own phone.
MapLab Survey handles RTK/GNSS point capture, drawing, area and volume calculations and coordinate conversion, then exports to DXF, KML/KMZ, GeoJSON, Shapefile, GeoPackage, NCZ or CSV. Capture, calculation and export work offline. Live NTRIP corrections and online basemaps need a connection.
Frequently asked questions
How is decare calculated?
Square metres divided by 1000.
Can a phone measure a field?
For approximate planning, yes.
How is perimeter measured?
By summing polygon sides.
How does MapLab Survey help?
It combines measurement and export.
Technical references
The field guidance in this article is aligned with the technical and official references below.
Related: Field area calculation · Area measurement app · Parcel area difference · MapLab Survey