Measure Your Plot and Compare It With SIGPAC

SIGPAC is Spain's official map of farm parcels, the one used for aid declarations, drawn over aerial photos. Other countries have their own version. The question is always the same: your plot looks bigger, or smaller, than the official figure, so who is wrong?

A worked case: 2.04 ha measured, 1.92 ha on paper

Trace a five-sided olive plot on the Satellite map: sides of 122.6, 130.7, 111.1, 99.9 and 88 m. The panel gives Area 20,442.8 m², which is 2.04 ha, and Perimeter 552.3 m. For the comparison, take a printout that says 1.92 ha for the same recinto.

Measured vs official, and the margins to judge the gap (computed)
	Figure
Measured in LandMeasure	20,442.8 m² (2.04 ha)
Official figure on the printout	19,200 m² (1.92 ha)
Difference	1,242.8 m², 6.5 % of the official figure
GPS margin if walked at ±4m	± 1,104.6 m² (± 0.11 ha)
GPS margin if walked at ±5m	± 1,380.8 m² (± 0.14 ha)
A 2 m strip along the whole edge	552.3 m × 2 m = 1,104.6 m²

Read the last row twice. Drawing the edge 2 m further out, all the way round, is worth as much as the whole walking margin. On a plot of two hectares, the line you choose decides the result more than the phone does.

In this case the gap (1,242.8 m²) is a little bigger than a ±4 m walking margin and inside a ±5 m one. That is not a finding. Before treating it as a real discrepancy, look for the gap to be clearly outside the margin from two separate measurements.

Where the difference usually comes from

Recinto, parcela, finca: a recinto is one land-use piece. Your finca can be several recintos, and a track or a ditch may sit in its own one. Compare like with like.
Which edge: wall, fence, centre of the ditch, edge of the crop. The official line was drawn by someone on a photo; yours by you.
Imagery offset: satellite photos can sit a few metres off the ground. Tracing a parcel on one photo and comparing with a line drawn on another adds that shift.
GPS error if you walked it. The panel's GPS margin shows the size.
Slope: both figures are flat, map areas. A steep plot has more ground than either number says.

How to measure a plot to compare

In Settings > Units, set Area to Hectares (ha) so the figure reads like the official one. Switch to Square Meters (m²) later to see the small differences.
Open the official viewer on another device, or a printout, and note which edges the recinto follows.
In LandMeasure, Map tab > Satellite, then Measure > Measure Area. Tap the corners along the same edges the official map uses.
If the boundary is not visible from above, walk it: walking-figure button, walk, stop button, then the green checkmark. Check the GPS margin line before you save.
Compare the gap with the margin. Inside it: the plot matches. Clearly outside it, twice: worth taking to someone who can correct the record.

One thing to know: you cannot load the official outline into LandMeasure and lay it over yours. There is no import of KML, GPX or shapefiles and no parcel data, so the comparison is two numbers and your eye, side by side.

Free and Pro, for this job

Measuring is free, with ads outside the Map screen. One measurement per project in the free version, so a finca with three recintos needs three projects, or LandMeasure Pro for all three in one project with a Total Area. The PDF Report that you could hand to an advisor, and the KML or CSV export, are Pro.

What makes this worth having before the paperwork is the GPS margin sitting right under the area. That is the number that actually tells you whether a gap is real or just noise.

Questions and answers

What does cadastral area mean?

It is the area recorded for a parcel in the official land register, usually a flat area worked out from the mapped boundary. It can differ from a field measurement because the mapped line and the line on the ground are not always the same.

How do I check the land area of a property online?

Use your country's official cadastre or agricultural parcel viewer for the registered figure. To measure it yourself, trace the boundary on the satellite map in LandMeasure; the app has no parcel data, so it will not fetch the official figure for you.

How do I measure agricultural land with a phone?

Trace the corners on satellite imagery or walk the edge with GPS using Measure Area. On a plot of a couple of hectares, tracing is usually tighter than walking: the walking margin above was about ± 0.11 ha.

Is a land survey area more accurate than an app?

Yes. A surveyor uses instruments far more accurate than phone GPS and works from the legal boundary. The app is for a quick, honest estimate with its margin shown.

How accurate is phone GPS for measuring land and property lines? · LandMeasure

Why does my own measurement of a farm plot not match the SIGPAC area?