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Rebuilding civilization

Geometry and measurement

Map and plan scale

Convert measurements from a map or plan to real life and back with 1:N scales.

The number N in the 1:N scale. Topographic maps, 1:25,000 or 1:50,000; house plans, 1:50 or 1:100.

cm

Result

Real distance
— m
Real distance in km
— km
Length on the plan
— cm

How it is calculated

At a 1:N scale, 1 cm on the plan is N cm in reality. Real = plan × N and plan = real ÷ N.

Example: on a 1:50,000 map, 4 cm are 200,000 cm = 2000 m = 2 km. Trick: at 1:50,000 each centimetre is half a kilometre; at 1:25,000, a quarter of a kilometre.

Keep in mind

  • If the plan has been photocopied or printed at another size, the numeric scale no longer holds: use the graphic scale (the drawn bar) or a known distance to work it out again.
  • Distances measured on a map are horizontal: in the mountains the real walking distance is longer (use the slope tool).

See also

More tools in “Geometry and measurement”