Scale shows how distance on the map compares to real distance on the ground. It lets us convert a short map measurement into an actual distance.
Types of scale
- Statement scale: written in words, e.g. 1 cm represents 1 km.
- Representative fraction (RF): a ratio such as 1:50 000, meaning 1 unit on the map equals 50 000 of the same units on the ground.
- Linear (line) scale: a marked bar you can measure against directly.
Key idea
On a 1:50 000 map, 2 cm on the map equals 1 km on the ground, and each grid square measures 1 km × 1 km = 1 km².
Measuring distance
A straight distance is measured with a ruler, then multiplied using the scale. A winding distance (such as a river or road) is measured with a piece of thread or the edge of paper laid along the curve, then straightened and read against the scale.
Calculating area
For a regular shape, area = length × width, then convert using the scale. For an irregular shape, count grid squares: count every complete square, then add squares that are half or more covered and ignore those less than half covered.
Example
On a 1:50 000 map, a forest covers 6 full squares and 4 squares that are more than half filled. Estimated area = 6 + 4 = 10 km².
Remember
- 1:50 000 means each grid square is 1 km².
- Use thread for winding distance, a ruler for straight distance.
- Count a part-square only if half or more is covered.