GCSE Maths · Ratio & proportion

Scale drawings GCSE Questions and Worked Answers

A scale drawing keeps lengths proportional. A scale 1:n means one drawing unit represents n of the same real units. Multiply a drawing length to find the real length; divide a real length to find its drawing length, keeping units consistent.

Foundation & Higher6 worked examples10 original questions
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Start with the meaning

What you need to know about scale drawings

A map can show a long road on a small page. If each 1 cm of map represents 4 m of real distance, a 3 cm line represents 12 m. The map and the real object have corresponding lengths linked by one multiplier. That relationship is the scale.

See the idea first

One map unit always represents the same real distance

A scale can carry units, such as 1 cm : 4 m. To write it as the plain ratio 1 : n, first use the same units: 4 m = 400 cm, so this is 1 : 400. That means 1 drawing centimetre represents 400 real centimetres. A plain ratio does not secretly switch from centimetres to metres.

Scale: 1 cm on the drawing represents 4 m in reality
Drawing lengthReal lengthCalculation
1 cm4 m1 × 4
3 cm12 m3 × 4
5.5 cm22 m5.5 × 4
From problem to method

Typical problems you need to be able to solve

These are the main kinds of question in this topic. Each card first states the problem, then explains how to solve it.

Find a real distance

What the problem asks: At 1 cm : 3 km, what real distance does 4.5 cm represent?

How to solve it: Multiply 4.5 by 3 to get 13.5 km. The scale already states the different units explicitly.

Find a drawing length

What the problem asks: A real wall is 8 m long. Draw it at scale 1 : 200.

How to solve it: Convert 8 m to 800 cm, then divide by 200. Its drawing length is 4 cm.

Find the scale

What the problem asks: A 6 cm drawing line represents a 15 m wall. Write the scale as 1 : n.

How to solve it: 15 m = 1500 cm. The ratio 6 : 1500 simplifies by dividing both sides by 6 to 1 : 250.

A reliable routine

Convert between a drawing and reality

Use this for a proportional scale drawing or map. Matching lengths share the same ratio, so you can multiply or divide by the real distance represented by one drawing unit.

  1. Write what one drawing unit represents, including units.
  2. Convert units first if using a plain ratio 1:n.
  3. For scale 1 : n in matching units, multiply the drawing length by n to find the real length; divide the real length by n to find the drawing length.
  4. Check that the real object is larger for a reducing scale; square the factor only for areas.

Check: Do not measure a responsive webpage diagram with a ruler: screen size and zoom change it. These questions provide drawing measurements or ask you to construct a measured drawing on paper.

Fully worked

Scale drawings GCSE worked examples

Each solution explains the clue, why the method fits and how to check the result.

Example 1

Map distance

2 marks
Question

A map uses 1 cm : 2.5 km. A route measures 6 cm on the map. Find its real length.

6×2.5=15 km6\times2.5=15\text{ km}

Each map centimetre contributes 2.5 km.

Example 2

Ratio scale

3 marks
Question

A plan has scale 1 : 500. A wall measures 3.4 cm on the plan. Find its actual length in metres.

3.4×500=1700 cm3.4\times500=1700\text{ cm} 1700÷100=17 m1700\div100=17\text{ m}

A plain ratio gives the real length in the drawing's unit, centimetres, so convert to metres at the end.

Example 3

Drawing length

3 marks
Question

A room is 7.2 m long. Find its plan length in cm at scale 1 : 120.

7.2 m=720 cm7.2\text{ m}=720\text{ cm} 720÷120=6 cm720\div120=6\text{ cm}

Divide because the drawing is smaller than the room.

Example 4

Find the scale

3 marks
Question

A 4 cm model length represents 10 m. Give the scale as 1 : n.

10 m=1000 cm10\text{ m}=1000\text{ cm} 4:1000=1:2504:1000=1:250

Divide both ratio terms by 4.

Example 5

A complete room plan

4 marks
Question

A room is 6 m by 4.5 m. At scale 1 : 150, state the dimensions of the rectangle to draw in centimetres.

Convert the real dimensions: 600 cm and 450 cm.

600/150=4 cm600/150=4\text{ cm} 450/150=3 cm450/150=3\text{ cm}

Draw a 4 cm by 3 cm rectangle with right angles; apply the same scale to both dimensions.

Example 6

Area scale

4 marks
Question

At scale 1 : 100, a rectangular plan area is 12 cm². Find the real area in m².

Each length grows by 100, so area grows by 100².

12×1002=120000 cm212\times100^2=120000\text{ cm}^2 120000/10000=12 m2120000/10000=12\text{ m}^2

Equivalently 1 drawing cm represents 1 real m, so 1 drawing cm² represents 1 real m².

10 original questions · total 29 marks

Scale drawings GCSE exam-style questions

Try each question before opening its fully worked answer. The difficulty rises through the set.

Before you startAllow about 34 minutes · Show your working. Give exact answers unless a question asks you to round, and include units where needed. · answers start collapsed
1

Simple map scale

2 marks

At 1 cm : 5 km, find the real distance represented by 2.4 cm.

Show worked answer
2.4×5=12 km2.4\times5=12\text{ km}
2

Real distance

3 marks

A drawing at 1 : 200 shows a line 8 cm long. Find its real length in metres.

Show worked answer
8×200=1600 cm=16 m8\times200=1600\text{ cm}=16\text{ m}
3

Model length

3 marks

A real length is 9 m. Find its drawing length at 1 : 300 in cm.

Show worked answer
9 m=900 cm9\text{ m}=900\text{ cm} 900/300=3 cm900/300=3\text{ cm}
4

Map length

2 marks

At 1 cm : 4 km, how long should a 30 km route be on the map?

Show worked answer
30/4=7.5 cm30/4=7.5\text{ cm}
5

Write 1:n

3 marks

A 5 cm line represents 20 m. Find the scale as 1 : n.

Show worked answer

20 m = 2000 cm.

5:2000=1:4005:2000=1:400
6

Different drawing units

3 marks

At scale 1 : 50,000, a line is 36 mm long. Find the real length in km.

Show worked answer
36×50000=1800000 mm36\times50000=1800000\text{ mm} 1800000/1000000=1.8 km1800000/1000000=1.8\text{ km}
7

Two dimensions

3 marks

A garden is 12 m by 8 m. Give its plan dimensions in cm at 1 : 400.

Show worked answer
1200/400=3 cm1200/400=3\text{ cm} 800/400=2 cm800/400=2\text{ cm}

Draw a 3 cm by 2 cm rectangle.

8

Perimeter

3 marks

At scale 1 : 250, a plan rectangle is 4 cm by 2 cm. Find the real perimeter in metres.

Show worked answer

Real sides are 1000 cm = 10 m and 500 cm = 5 m.

P=2(10+5)=30 mP=2(10+5)=30\text{ m}
9

Area

4 marks

At scale 1 : 200, a plan area is 6 cm². Find the real area in m².

Show worked answer
6×2002=240000 cm26\times200^2=240000\text{ cm}^2 240000/10000=24 m2240000/10000=24\text{ m}^2
10

Same line, different scale

3 marks

A route is 5 cm on a 1 : 20,000 map. How long is it on a 1 : 50,000 map?

Show worked answer

Real length = 5 × 20,000 = 100,000 cm. On the second map:

100000/50000=2 cm100000/50000=2\text{ cm}

The larger second number in the scale 1 : n produces the smaller drawing.

Examiner-style feedback

Common scale drawings mistakes

Mixing ratio units

Convert both lengths to the same unit before simplifying to 1:n.

Multiplying a real length

For a reducing scale, finding the drawing length requires division.

Scaling area like length

Area changes in two dimensions, so square the length factor.

30-second recap

Choose, carry out, check

Translate the wording before you reach for a rule.

  1. Read one-unit correspondence.
  2. Use equal units in plain ratios.
  3. Choose multiply or divide from the direction.
  4. Area uses the square factor.
Quick answers

Scale drawings FAQ

Is 1:100 a larger drawing than 1:500?

For the same object, yes. Each real length is divided by 100 rather than by 500.

Can I use metres on both sides of a ratio?

Yes. A plain ratio works in any common unit; both sides must use the same one.

Build connected skills

What to revise next

Content standards

Curriculum and rights review

R2/G15 scale diagrams and maps across tiers, with G19 area factors as a connected extension. On-screen artwork must not be physically measured unless a calibrated scale is provided. Questions, suggested marks, solutions and diagrams are original practice material, not official past-paper questions.

Official specification references