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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 2.5cm in the blueprint. How long is that in real life?

2.5cm 100 = 250cm = (250 ÷ 100)m = 2.5m, 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 10cm long. How long is the car in real life?

10cm 45 = 450cm = (450 ÷ 100)m = 4.5m, 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 1.8cm long. How long is the tadpole in the drawing?

1.8cm 10 = 18cm,

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

A smiling tadpole

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