---
title: "Graphical scale and its importance"
subject: "Surveying I"
chapter: 1
key: "semester_3/surveying_i:graphical-scale-importance"
source: https://www.bctengineer.com/q/semester_3/surveying_i/graphical-scale-importance
site: BCT Engineering
---

# Graphical scale and its importance

Surveying I · Chapter 1: Introduction

- Asked in: 2070 Chaitra (old course), 4 marks
- Video: [Graphical Scales v/s Numerical Scales | Surveying Explained Notes](https://www.youtube.com/watch?v=bRYPlGxRqMQ) — Simplified Learning Civil Engineering
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/surveying_i/graphical-scale-importance
- Whole chapter: https://www.bctengineer.com/md/semester_3/surveying_i/chapter-1

## Question

What is a graphical scale? Explain its importance on the map.

## Short answer

A graphical scale is a bar scale on a map divided into ground units. It remains accurate if the map shrinks or is enlarged, allows direct distance measurement without calculation, and is easy to use with a divider or by eye.

## Answer

A **graphical scale** (bar scale) is a line drawn on the map and divided into units that represent real ground distances, e.g. a bar marked 0, 100, 200, 300 m. Plain, diagonal and vernier scales are graphical scales.

#### Importance on the map
1. **Distances can be read directly** without calculation; the user need not know the RF.
2. **It is unaffected by shrinkage or enlargement.** Paper expands or shrinks with weather, and a map may be photocopied, enlarged or reduced. A numerical scale (1:5000) would then be wrong, but the graphical scale changes together with the map, so it stays correct.
3. **Clear even to non-technical users**, who can compare the bar with the map features by eye or with a divider.
4. **Easy to use with a divider or strip of paper** for measuring curved lengths.
5. **Gives an idea of the area size** at a glance.
6. **Accuracy.** A diagonal or vernier graphical scale can read up to a very small unit.

For these reasons, a graphical scale is always shown on a map along with the numerical RF.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Why is a graphical scale better than a numerical scale when a map is photocopied or enlarged?
   A. It is always printed in a larger font
   B. It changes along with the map so stays correct
   C. It does not need the divider
   D. It is stored in the legend
   Answer: B. The bar scales with the paper, whereas an RF such as 1:5000 would be wrong. (Key point: Shrinkage)

2. A graphical scale allows distances to be
   A. read directly without calculation or knowing the RF
   B. calculated using the RF only
   C. read only by technical users
   D. found without a divider only
   Answer: A. No arithmetic is needed. (Key point: Direct reading)

3. Which are graphical scales?
   A. RF and statement scales
   B. Only the scale of chords
   C. Only the 1:5000 type
   D. Plain, diagonal and vernier scales
   Answer: D. Plain, diagonal and vernier scales are graphical. (Key point: Types)

4. A graphical scale is shown on a map
   A. instead of the RF always
   B. only on small maps
   C. along with the numerical RF
   D. only for diagrams
   Answer: C. Both are given. (Key point: Use on maps)

## Related in Surveying I

- [Diagonal scale: Kathmandu-Pokhara highway map](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Adiagonal-scale-kathmandu-pokhara-224) — Surveying I, chapter 1, asked 2×
- [Scale of a map and its classification](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Ascale-of-map-classification) — Surveying I, chapter 1
- [Scale for 1.5 km road on map](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Ascale-road-1-5-km) — Surveying I, chapter 1
- [RF and scale for 51072 m² plot](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Ascale-plot-51072-sqm) — Surveying I, chapter 1, asked 3×
- [RF and scale for 6.304 ha plot](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Ascale-plot-6-304-ha) — Surveying I, chapter 1, asked 3×
- [RF and scale for 51750 m² plot](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Ascale-plot-51750-sqm) — Surveying I, chapter 1, asked 3×

## Related in other subjects

- [Flying height from photo and map scale](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Aflying-height-pq-20cm-focal-24) — Surveying II, chapter 7