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 the tolerance first
A rough figure for planting, an area for a subsidy application and a boundary for a sale need three different levels of accuracy. Choose the method after you know which one you need.
Walking versus drawing
Walking the boundary captures the real shape including the awkward corners; drawing on imagery is faster and cleaner but inherits any shift in the image.
Corners, not steps
Record a point at each corner and let the straight sections run between them. Continuous tracking adds noise that inflates both area and perimeter.
Close the loop and check
Return to the first corner and confirm the polygon closes. Then note the coordinate system next to the area, or nobody can verify the figure later.
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