Understanding Scales and Scale Drawings - A Guide (2024)

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

When a drawing is described as ‘to scale’, it means that each element in that drawing is in the same proportion, related to the real or proposed thing – it is smaller or indeed larger by a particular percentage.

If something is ‘drawn to scale’ we expect that it has been drawn, or printed, to a common scale that is used as standard in the construction industry. As we gain a better understanding of scale, we can view a drawing in a particular scale and instantly recognise and understand the spaces, zones and gain a quick understanding of the existing or proposed spatial relationships.

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 50unit 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.

Understanding Scales and Scale Drawings - A Guide (1)

The image above shows an example of a drawing set with different scales to demonstrate different aspects of the design. (cad drawing courtesy of bibliocad.com). You may want to represent a site plan at a scale of 1:500, but perhaps show floor plans at 1:100 for example.

Working with scales for architectural representation

In architecture, we use a collection of standard scales to represent our designs. For example, it is common practice to produce floor plans at a scale of 1:100 (dependent on size of project and paper). Once you gain an understanding of scales, it is easy to understand which scale is most suited to which type of drawing.

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Scale bar blocks courtesy of cad-blocks.co.uk.

These scale bars show what one unit represents at different scales.

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 below, and not make up your own.

What scale should I use?

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.

Location Plan and Key Plans

1:1250 (often requested by planners)



Site Plans, Sketch schemes etc



Plan drawings – floor plans, elevations, sections



Room plans, interior elevations


Component / detail drawings



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Working out the scale

A scale is shown as a ratio, for example 1:100.A drawing at a scale of 1:100 means that the object is 100 times smaller than in real life scale 1:1. You could also say, 1 unit in the drawing is equal to 100 units in real life.

So, if we were drawing a table that measured 100cm wide by 200cm long at a scale of 1:50, you would draw the table 2cm wide by 4cm long on your piece of paper. This is worked out by dividing the real life size (100cm) by 50 (1:50 scale). This gives you a result of 2cm. For the length of the table we divide 200cm by 50 to get a result of 4cm.

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Of course, it is not necessary to calculate the required measurements when you draw. You can either use a scale ruler to hand draw your plans, or software such as Revit, AutoCAD, ArchiCAD that will allow you to present your drawings at any scale and easily switch between scales as required.

How to use a scale ruler

A scale ruler is a tool that architects, engineers and designers use to draw their designs at an appropriate scale that it fits on a piece of paper and is in proportion to accurately convey the scheme. The scale ruler comes in different shapes, flat or triangular but they all provide sets of graduated numbered spaces, that establishes aproportion of one unit to thespecified unit,i.e. different scales. As an example, the ruler I have in front of me now has the following scales; 1:1, 1:100, 1:20, 1:200, 1:5, 1:500, 1:1250, 1:2500.

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Scale rules have varying number ofscales on them, depending ontheir intended use. Using a scale rule is pretty easy when you know how.

When you are drawing a plan, you select the scale you intend to use by turn the ruler to the appropriate side. You can then draw the line to the desired measurement using the scale ruler. For example, if you have select to draw a 5m wall at 1:100, you would select your 1:100 side of the ruler, and draw 5 units along the ruler, as each unit represents 1m.

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When you are reading plans, you establish the scale of the drawing or plans, and select that scale on your ruler, you are then able to measure the lines using the correct scale.

How to scale a drawing up or down

Let’s look at converting a scale drawing to a different scale. You can considering changing the scale of a drawing by a decimal factor or by a percentage. For example, lets imagine we have a drawing at 1:50, but we want amend the scale, to show that drawing at 1:200. A drawing at 1:200 is 4 times larger than a drawing at 1:50, therefore we would need to increase the size of the drawing 4 x. The table below demonstrates the different scale factors required to convert a scale up or down.

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Table: Converting scales up or down

Being able to scale drawings up and down using percentages has become very useful too. Working in Adobe (Photoshop, InDesign etc), you will find you can adjust the size of an object using a percentage, which is great if you are wanting to accurately scale a drawing up or down while working in photoshop while maintaining a precise scale.

Lets imagine you are working on a drawing that you have imported into an A4 sized photoshop document. The drawing you have imported does not quite fit at its current scale of 1:50, so you will need to reduce the scale in order to squeeze the image onto the page, while maintaining an accurate scale. By using the table below, we can see that to convert from a scale of 1:50, down to 1:100 we would need to reduce the drawing by 50%. To do this we would make sure the dimension ratios of the image are locked, and proceed to type 50% into the size box.

Obviously this is a simple example but you get the idea. The table below provides the basic conversion percentages to scale a drawing up or down using the standard metric scales.

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Table: Converting scales up or down

Paper size scales and magnification

We can now look at amending paper size scales and magnification. There are times when you may have a drawing on an A4 piece of paper, that you need to scale up to an A3 piece of paper for example. Let’s imagine you were needing to trace this drawing so would use a photocopier to scale the drawing up to the necessary size.

How to convert paper sizes?

To convert the paper size you can use the percentages in the table below. Note that these percentages do not correspond to the scale factors. So, if you scale or magnify a paper size accurately, it does not mean that you will retain an accurate (or standard) scale of the drawing. So, if you want to increase the scale of a drawing using a photocopier, but want to increase it to a standard scale (1:10 for example) then you must use the percentage factors for converting scale. If it is just the paper size you wish to change, then you can use the paper size converter. I hope that makes sense.

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Table: Converting paper sizes and magnification factors

Working with paper sizes

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.

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This basic format of 1m2then 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.

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Working with scales digitally

One of the great things about using digital drafting software is that you can produce drawings as multiple scales from one single drawing. Programs such as Revit, AutoCAD, ArchiCAD and many more, allow you to draw up your designs at 1:1 scale, that is real life size, and produce drawings or plots of these designs at an appropriate scale for the paper size you have selected.

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 dynamic scale bar cad blocks here:


You can download a handy pdf of this post by clicking the download button below!

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 (emma@firstinarchitecture.co.uk) or comment below

Understanding Scales and Scale Drawings - A Guide (2024)


How do you find the scale and scale factor of a drawing? ›

The basic formula that is used for calculating the scale factor is, Scale factor = Dimension of the new shape ÷ Dimension of the original shape. In case, if the original figure is scaled up, the formula is written as, Scale factor = Larger figure dimensions ÷ Smaller figure dimensions.

What are the 4 main types of scales used for drafting? ›

Scales used in drafting include the mechanical engineer's scale, the civil engineer's scale, the architect's scale, and the metric scale.

How do you read scale drawings? ›

A scale is shown as a ratio, for example 1:100. A drawing at a scale of 1:100 means that the object is 100 times smaller than in real life scale 1:1. You could also say, 1 unit in the drawing is equal to 100 units in real life.

What is an example of a scale drawing in math? ›

A scale drawing is a two-dimensional representation of an actual object or place. Maps and floor plans are some examples of scale drawings.

What is a scale answer the question? ›

Scale is the distance between two points on the map to the actual distance between two points on earth. The reduction in the size of the actual region according to the fixed ratio while mapping is called scaling down. For example : 1 cm distance on a map is equal to 100 km on real earth.

What is the formula for scale drawing? ›

So when you're working with scale drawings: Find out what the scale on the drawing is. Measure the distance on the drawing using a ruler (or count the number of squares, if that's an option). Multiply the distance you measure by the scale to give the distance in real life.

What is the easiest way to find the scale factor? ›

How to find scale factor
  1. Scale Up (smaller to larger) = larger measurement / smaller measurement.
  2. Scale Down (larger to smaller) = smaller measurement / larger measurement.
Jan 11, 2023

What is the standard scale for drawing? ›

Referred to as 1:10, 1:20, 1:30,1:40, 1:50 or 1:60 scale. Typically in civil engineering applications, 1:10 (1″=10′) is used exclusively for detail drawings. 1:20 and 1:40 scales are used for working plans. 1:60 is normally used only to show large areas of a project.

What are the 3 types of scale patterns? ›

There are three types of minor scales commonly found in music composition.
  • Natural Minor Scale.
  • Harmonic Minor Scale.
  • Melodic Minor Scale.

How do you explain scale in art? ›

Scale refers to the overall physical size of an artwork or objects in the artwork. We always relate scale to the size of the human body - how big or small the piece is in relation to us. An artist may decide to use a scale which is different from life-sized and this will have an impact on how it feels.

What are different drawing scales? ›

The scales in engineering drawing are classified as the following: Plain scale. Diagonal scale. Vernier scale.

How do you accurately read a digital scale? ›

If you want your scale reading to be as accurate as possible, here are some tips to reduce measurement error.
  1. Ensure that the scale is level and on a hard surface.
  2. Allow your digital scale to self calibrate. ...
  3. Weigh yourself at the same time of day, preferably in the morning before eating or drinking anything.
May 1, 2019

What is scale drawing in simple words? ›

Definition: Scaled Drawing. A drawing that shows a real object with accurate sizes reduced or enlarged by a certain amount (called the scale).

What is a real life example of a scale drawing? ›

Road maps are another common example of a scale drawing. Builders use blueprints to erect buildings, bridges, and other structures. Blueprints are also scale drawings. Directions for assembling a bookcase or other objects might include a scale drawing.

What are the different types of scale explain with example? ›

Introduction: There are 4 types of scales, based on the extent to which scale values have the arithmetic properties of true numbers. The arithmetic proper- ties are order, equal intervals, and a true zero point. From the least to the most mathematical, the scale types are nominal, ordinal, interval, and ratio.

How do you explain a scale to students? ›

Scale factor is the number used to multiply one object by to get another object that looks the same but is a different size. It makes an exact copy only larger or smaller than the original. Scale Factor multiplies the picture or object just as if you enlarged or shrank it on a copy machine.

How do you explain scale of measurement? ›

Scales of measurement refer to ways in which variables/numbers are defined and categorized. Each scale of measurement has certain properties which in turn determines the appropriateness for use of certain statistical analyses. The four scales of measurement are nominal, ordinal, interval, and ratio.

How do you identify a scale? ›

A major scale always starts and ends on notes of the same letter name, one octave apart, and this starting and ending note determines the name of the scale. Therefore, Example 1 depicts a C major scale because its first and last note is a C.

What are examples of scale? ›

For example, a scale of 1:10 means that the size of 1 unit in the drawing would represent 10 units in the real world. For example, if a lion is of height 50 inches in the real world and is represented as 5 inches on the drawing, it shows that a scale of 1:10 has been used.

How do you draw a simple map scale? ›

Here are four simple steps you'll want to follow:
  1. Find a map of an area you want to use.
  2. Find both the actual and measured distances of two points on your map.
  3. Divide the actual distance by the measured distance on the map for your scale.
  4. Place your scale numbers on the map.
Nov 22, 2022

What is a scale factor for dummies? ›

A scale factor is defined as the ratio between the scale of a given original object and a new object, which is its representation but of a different size (bigger or smaller).

What is a scale factor 7th grade math? ›

● Scale Factor: The ratio of any two corresponding lengths in two similar. geometric figures.

What is the scale factor worksheet? ›

The scale factor worksheets help the students grasp the concepts of scale drawings and models as well as geometrical drawings. Solving problems on scale factor will help the young minds understand how to compare two figures and understand their scale ratio.

How do you calculate scale? ›

You have to divide your real measurement to the model. For example, if your real measurement is 5m and your model is 20cm, divide 5/20 =1/4 and that means the ratio would be 1:4.

How do you scale a drawing plan? ›

The easiest way to make a scaled drawing plan is by using graph paper. To use this method you are basically counting squares as feet. For example, if your wall was 12′ 6″ (twelve feet, six inches) your line would be 12 1/2 squares long. Your windows would convert from 3′ (feet) to 3 squares.

What does scale 1 to 200 mean? ›

1: 200 scale: means 1 metre on the map represents 200 metres on the ground.

How do you find the scale of a drawing area? ›

To calculate actual area based on a scale drawing, take each of the original dimensions and multiply them by the scale factor to get the actual dimensions. Then, use your knowledge of geometric figures to calculate the enlarged or reduced area.

What are the types of scale drawing? ›

Five different types of scale drawings and plans are generally used in planning:
  • location plans.
  • floor plans.
  • roof plans.
  • elevations.
  • sections.

What is scale method? ›

Definition: Scaling technique is a method of placing respondents in continuation of gradual change in the pre-assigned values, symbols or numbers based on the features of a particular object as per the defined rules. All the scaling techniques are based on four pillars, i.e., order, description, distance and origin.

What is the correct method of using a scale? ›

(1) The scale should be placed to the side of the object being measured. It should also be in touch with the object being measured. (2) While reading the scale, eye must be placed vertically above the scale mark being read.

What scale are detailed drawings? ›

Typically in civil engineering applications, 1:10 (1″=10′) is used exclusively for detail drawings. 1:20 and 1:40 scales are used for working plans.

What scale should drawings be? ›

A full size drawing would be 1:1 (or sometimes 1/1 or 'one to one'). A half size drawing would be 1:2. A tenth size drawing would be 1:10. A double size drawing would be 2:1.

What does a scale of 1 to 500 mean? ›

A scale of 1:500 means that the actual real-life measurements are 500 times greater than those on the plan or map. This means that it does not matter whether you take the measurements on the plan in millimetres (mm), centimetres (cm) or metres (m) – the measurements will be 500 times as much in real life.

What is 1 100 vs 1 200 scale? ›

In a drawing at scale 1:50, there is 1 unit for every 50 unit in real life, at scale 1:100 there is 1 unit for every 100 units in real life and at scale 1:200 there is 1 unit for every 200 units in real life. And so on. It is worth noting that scale drawings represent the same units.

What do scale numbers mean? ›

The "scale" of a model is it's size relative to the size of the "real" version. So compared to a 1:24 scale model, the real version is 24 times larger in size or 1:1 in scale. Example; In the pictures below... The model on top is "1:18 Scale", which means it is one eighteenth the size of the real thing.

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