Wednesday , 22 November 2017

Understanding Scales and Scale Drawings

Scale drawings allow us to accurately represent sites, spaces, buildings and details to a smaller or more practical size than the original.

In the real world, one meter is equal to one meter.  A drawing at a scale of 1:10 means that the object is 10 times smaller than in real life scale 1:1. You could also say, 1 unit in the drawing is equal to 10 units in real life.

As the numbers in the scale get bigger, i.e. 1:50 – 1:200, the elements in the drawing actually get smaller. This is because in a drawing at 1:50 there is 1 unit for every 50 unit in real life. A drawing of 1:200 is representing 200 units for every one unit – and therefore is showing the elements smaller than the 1:50 drawing.

It is worth noting that scale drawings represent the same units. So, if a drawing is at 1:50 in cm, 1cm in the drawing will be equal to 50cm in real life. Similarly, if a drawing is in mm, at 1:200 – one mm unit in the drawing will represent 200mm in real life.

The image above shows an example of a drawing set with different scales to demonstrate different aspects of the design. (cad drawing courtesy of You may want to represent a site plan at a scale of 1:500, but show floor plans at 1:100 for example.
Scale bar blocks courtesy of These scale bars show what one unit represents at different scales.

The following looks at the recommended scales for architectural use in the metric system. The chosen scale and paper size will often depend on the size of site/design of each individual project.


Site and Key Plans


Sketch schemes etc


Location / Plan drawings


Component / detail drawings

The general requirement of a scaled drawing is to convey the relevant information clearly with the required level of detail. If you are working in practice there will often be office standards. For example, they may only use layout sheets of either A3 or A1 – depending on the scale of the project and information that is being represented. As a student, you need to make these decisions based on industry standard. It is always best to use a ’round’ scale, i.e., one of the scales mentioned above, and not make up your own.
When working with ISO paper layouts we know that the standard size of paper was developed on the basis of an area of 1m2, divided according to the ratio of the sides.
This basic format of 1m2 then forms the basis for all other smaller sizes. All A sized paper is either halving or doubling the basic format.
X x Y = 1
Below is a list of all the A paper sizes.
When working in CAD you can let the software do some of the hard work for you by making use of the paper space option to create layouts. On your layout sheet you are then able to create viewports which feature your drawing at the required scale. I have recorded a couple of tutorials that will help with setting up drawings for printing at appropriate scales.


I have also recorded a tutorial that explains how to scale a drawing in cad. This is useful if you have imported a drawing at a different scale.

You can download my scale bar cad blocks here:
 Hope you find this useful, if you have any questions, or there is something else you would like to know about, please drop me an emaill ( or comment below 🙂

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