Use this cartographic calculation to convert, scale, or compare map, terrain, bearing, raster, or route quantities when the coordinate and unit conventions are explicitly known.

Radius Millimeters (mm)

Required number input.

Area Square Millimeters Per Unit (mm2/unit)

Required number input.

Value represented by a circle radius at a specified square-millimetres-per-unit scale. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Value

The resulting value returned as a number.

• Map calculations depend on datum, projection, latitude, scale definition, magnetic-declination epoch, and whether distances are planar, rhumb-line, or geodesic. A compact formula cannot remove distortion or infer the missing reference system.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Confirm the map datum, projection, scale, and bearing convention before applying the result. Use geodesic or GIS software with current reference data when survey-grade or navigation-critical accuracy is required.

• Proportional Symbol Radius

  Circle radius in millimetres whose area is proportional to value at a specified square-millimetres-per-unit scale.

• Dot Density Dots Per Unit

  Count of map dots needed for a value when one dot represents a fixed number of units.

• Plan Area To Real Area

  Ground area in square metres represented by a plan area in square centimetres at scale 1:N.