Measuring on a map · 4 min
Draw a radius and find what is inside
Circles on a map: delivery zones, 'within 10 miles' and how area grows with the radius.
Measuring on a map
Everything within a distance
A radius circle holds every point within a set straight-line distance of a centre. 'Within 10 miles of the shop' is a radius.
People use it for delivery zones, school catchments, sales territories and 'how many cafés are near this flat?'.
Lesson notes
Everything from the cards above, on one page to come back to.
Everything within a distance
A radius circle holds every point within a set straight-line distance of a centre. 'Within 10 miles of the shop' is a radius.
People use it for delivery zones, school catchments, sales territories and 'how many cafés are near this flat?'.
Area grows faster than the radius
A circle's area is π × radius × radius. Because the radius is multiplied by itself, doubling it gives four times the area, not twice.
That matters when you price a delivery zone or count customers: going from 5 km to 10 km covers four times the ground.
Radius 10 km: 3.1416 × 10 × 10 ≈ 314 km²
A radius is not a travel time
A circle ignores rivers, motorways and one-way streets. Two homes on the edge of a 5 km circle might be 6 minutes or 40 minutes away by road.
Use a radius for 'how far, as the crow flies' and as a quick first filter. For 'how long to get there', you need a travel-time map, which is a different tool.
Questions
How do I draw a radius on a map?
Open MapGO's radius tool, click the centre and set the distance. It draws the circle and shows its area.
What is the difference between a radius and a buffer?
A radius is a circle around a point. A buffer is the same idea around any shape: a band of set width around a line, such as a road, or around an area.