How to Read Blueprint Scale

Here, you will see how scales are used in blueprints. We can have a blueprint for lots of things, for example a house, a room, or the parts of an iPhone.

For a blueprint to be practical, we need to choose a scale that fits the thing we want to make a blueprint of. Things that are very small have to be drawn larger, while very large things have to be drawn smaller, just like we did with the maps.

Blueprint of a house with scale 1:100

In the figure above, you can see a blueprint of a living room with a scale of $1 : 100$ . It’s practical to use a blueprint like this when you redecorate your house, just to see how you can place your furniture.

Example 1

A room is drawn with a scale of $1 : 100$ . The sofa is $2.5 cm$ in the blueprint. How long is that in real life?

\begin{array}{l} 2.5 cm \cdot 100 & = 250 cm \\ = (250 \div 100) m \\ = 2.5 m, \end{array}

which means the sofa is

2.5

meters long in real life.

Example 2

You have been given a model car for Christmas. On the box it says that the car is made with a scale of $1 : 45$ . The car you got is $10 cm$ long. How long is the car in real life?

\begin{array}{l} 10 cm \cdot 45 & = 450 cm \\ = (450 \div 100) m \\ = 4.5 m, \end{array}

which means that the real car is

4.5

meters long.

A sportscar

Example 3

You have captured a tadpole and want to examine it. You look online and find a drawing with a scale of $10 : 1$ . In reality the tadpole is $1.8 cm$ long. How long is the tadpole in the drawing?

1.8 cm \cdot 10 = 18 cm,

which means that the tadpole in the drawing is $18$ cm long.

A smiling tadpole

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How Does Scale Ratio Work?

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