How to Calculate Radius on a Map

Compass

Drawing a circle around a single point on a map creates an area. The distance from the middle of the circle to the edge of the circle is the radius. The radius shows how far a point is in a straight line. This is also known as distance as the bird flies.

Things You'll Need

• Map
• Compass
• Ruler

Instructions

1. Place the pointed end of the compass on a point on the map.

2. Place the pencil end of the compass on another point of the map and move the compass circularly to form a circle on the map.

3. Measure with a rule the distance from the center of the circle to an outside point of the circle. For example, three inches.

4. Convert the measurement in Step 3 to the proper scale. In example, if the map says one inch equals five miles, then the radius on the map equals fifteen miles.

References

• Maps: Radius Maps
• Free Map Tools: Radius Around A Point on a Map
• CSG Network: Mapping Scale Converter