Conversion of scale
Topic: Maps and Map Scale · NCERT: Class 11, Ch 2 "Map Scale"
Meaning
Conversion of scale means changing a map scale from one method to another. For example, you can change a statement of scale into a representative fraction (RF), or change it from the English system to the metric system. It matters because old maps used inches and miles, while modern maps use centimetres and kilometres. To convert, change both distances into the same unit, then compare them. Two key numbers help: 1 mile = 63,360 inches, and 1 km = 100,000 cm.
Example
An old map says "1 inch to 4 miles". Four miles is 4 × 63,360 = 253,440 inches, so the RF is 1:253,440. In metric units, 253,440 cm is about 2.53 km, so the same scale reads 1 cm to 2.53 km. In the same way, 5 cm to 10 km becomes 1:200,000.
Don't confuse with
- Measuring distance on a map: there you use the scale to turn a map length into a ground distance. In conversion, you change how the scale itself is written.
Related concepts
- Map scale
- Statement of scale
- Graphical scale
- Representative fraction
- Metric system of measurement
- English system of measurement