Measure the area of a field, a farm, a garden or a plot by walking around it with your phone. Open this
page on the phone, press Start at a corner and walk along the edge: the boundary draws itself on the
satellite map and the area grows as you go, in acres, hectares and square meters, with the distance
walked. Back at the start, press Finish. The walk becomes a shape you can straighten by dragging its
corners, save to your account, share by link or download as KML for Google Earth.
How do I measure land area with my phone's GPS?
Stand at one corner of the land, open this page in Safari or Chrome and allow location. Press
Walk, then Start walking, and walk along the boundary with the page
open. When you are back where you started, the page says so; press Finish. The area,
the perimeter and the distance walked are in the panel, and the shape stays on the map.
Trace my walk or Corners only?
Trace my walk puts a point every few meters as you go, which follows a curved edge, a
stream or a winding fence. Corners only adds a point only when you press
Mark corner, and each corner is the average of a few seconds of GPS, so stop for a
moment at each one. That is better for a field with straight sides. In either mode Mark corner pins a
precise point, and Undo removes the last one.
How accurate is GPS area measurement on a phone?
A phone's GPS is usually within 3 to 5 meters under open sky, and worse beside trees, buildings and
steep slopes. An error that shifts every point the same way, which is most of it, moves the shape
without changing its area; what changes the area is error across the edge. On a field of a hectare or
more, expect the area within a few percent. On a small garden or a house lot the error is a larger share,
and tracing the corners on the satellite photo is more exact. You can do both: walk it, then drag the
corners onto what you see. It is a measurement for planning, not a survey.
Does it keep measuring with the screen off?
No. Browsers stop giving a page GPS when it goes to the background or the screen locks, so the page keeps
the screen on while you walk. If the page is closed or reloaded, the walk comes back paused where it
stopped; press Resume to carry on. To record a whole hike or ride in your pocket, use the Geo Tracker
app for iPhone.
Which units does it show?
Acres, hectares and square meters at once, and any of square feet, square kilometers or square miles
from Units. An acre is 4,046.86 square meters and a hectare is 10,000 square meters, about 2.47 acres.
The distance walked and the perimeter are in feet and miles or meters and kilometers.
Can I save or download the measurement?
Download gives you KML for Google Earth, GeoJSON or a CSV of the numbers; the .geomeasure file opens in
the Geo Measure app for iPhone, iPad and Mac. With an account, Save keeps it in My Data with its name, and
Share gives you a link to send. Your positions stay on your phone unless you save.
Is there an app?
Not for this tool yet. The nearest is Geo Measure, on iPhone, iPad and Mac, which measures area and distance on a map and saves each measurement as a document. Paid.
App Store
· Mac App Store
· More about Geo Measure
Related: the acreage calculator to trace land on a satellite map
from a computer, the map area calculator for any area or distance, and the
GPS tracker to record a walk, hike or ride as GPX.
