1. What is Map Scale?
Scale shows the relationship between map distance and the corresponding ground distance.
It is an essential element of a map.
Without a scale, a map is generally considered a sketch.
2. Three Methods of Showing Scale
1. Statement of Scale
2. Representative Fraction (R.F.)
3. Graphical/Bar Scale
3. Statement of Scale
Written in words.
Example: 1 cm represents 10 km.
Advantage: Very simple.
Limitation: Becomes invalid if the map is enlarged or reduced.
4. Representative Fraction (R.F.)
Expressed as a ratio, e.g. 1 : 50,000.
Means 1 unit on the map = 50,000 same units on the ground.
It is called the Universal Method because it can be converted into different measurement systems.
5. Graphical/Bar Scale
Shown as a line divided into equal parts.
Can show kilometres, metres, miles, etc.
Main advantage: Remains useful even when the map is enlarged or reduced.
6. Systems of Measurement
Metric System
1 km = 1000 m
1 m = 100 cm
1 cm = 10 mm
English System
1 mile = 8 furlongs
1 furlong = 220 yards
1 yard = 3 feet
1 foot = 12 inches
7. Important Conversions
Statement → R.F.
Convert both distances into the same unit.
Example:
1 inch = 4 miles → R.F. = 1 : 253,440
R.F. → Statement
Convert the denominator into the required unit.
Example:
1 : 253,440 → 1 cm represents 2.53 km
⭐ Exam Focus
Universal method → R.F.
Best method after enlargement/reduction → Graphical scale
Simplest method → Statement of Scale
Map distance → Numerator
Ground distance → Denominator
📏 Important Terminology — Chapter 2: Map Scale
Term Simple Meaning
Scale Relationship-- between distance on a map and corresponding distance on the ground.
Map Distance --Distance measured between two points on a map.
Ground Distance --Actual distance between the same two points on the Earth's surface.
Numerator-- The number above the line in a fraction; in R.F., it represents map distance.
Denominator --The number below the line; in R.F., it represents ground distance.
Representative Fraction (R.F.)-- Scale expressed as a ratio, e.g. 1 : 50,000.
Statement of Scale Scale expressed in words, e.g. 1 cm represents 10 km.
Graphical Scale --Scale represented by a line/bar divided into equal parts.
Bar Scale-- Another name for graphical scale.
Primary Division Main divisions of a graphical/bar scale.
Secondary Division --Smaller subdivisions used for measuring shorter distances.
Metric System Measurement system using km, m, cm and mm.
English System Measurement system using miles, furlongs, yards, feet and inches.
Conversion of Scale --Changing one form of scale into another, such as R.F. into statement scale.
Universal Method-- Representative Fraction, because it can be understood and converted into different measurement systems.
Scale Reduction --Decreasing the size of a map.
Scale Enlargement --
Increasing the size of a map.
⭐ Most Important for Exams
Scale → Statement of Scale → R.F. → Graphical/Bar Scale → Numerator → Denominator → Map Distance → Ground Distance → Primary Division → Secondary Division → Metric System → English System → Conversion of Scale.
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