Scale Diagrams

Scale Diagrams (or drawings) are often used to represent a smaller or larger object, shape or image.

The scale used will depend on the reduction or enlargement of the object. For more on Scale Factors click here.

Typically the following scale ratios will be used:

A medium sized wall map of the World

Scale: 1:30,000,000 which represents 1cm to 300km

A road map for motorists

Scale: 1: 250,000 which represents 1 cm to 2.5km

An Ordnance survey map for walkers or hikers

Scale: 1:25,000 which represents 1cm to 250m

An architects drawing

Scale: 1:100 which represents 1cm to 1m


In the ordnance survey image above the distance between Piccadilly Circus and Leicester Square station entrances is 3.5cm (when viewed on a desktop). The distance between the station entrances is actually around 400m.

Tips when using scale diagrams

If you have to calculate using an image from a diagram remember to measure the distance accurately with your ruler. Then make a note of the scale of the diagram that will be given to you. You can then use this information to calculate the real distances or sizes.

If you are expected to draw your own map or diagram remember to decide on a suitable scale, write down the real distance or size, then calculate the scaled down lengths and make sure you then draw the plan accurately. 


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