Why do I need my plans to scale?

  • Posted on: 3 January 2015
  • By: Jennifer


Whenever you visit a display home or inspect a home that is for sale, builders or real estate agents will often hand out a floor plan. For most people this is quite helpful as it gives them a better overall picture of what they may be buying. The problem, though, with most of these plans is that they are not to scale. “Why is this a problem?” I hear you ask. Well if you are working with a plan that is not to scale, how can you measure anything? Do you want to have a clear understanding of how big your garden will be? Or do you want to know if your existing furniture will fit? If you want to feel confident that you truly understand what is happening in your home, then you do need your plan to scale.

How do you do scale house plans?

Simple. One quick calculation and a minute on a photocopier or home printer these days and you will be done. Please watch the accompanying video for how to convert any house plan to a usable scale. For this you only need: a. your plan b. a ruler c. a calculator and d. a photocopier or printer that can reduce and enlarge.

Step 1: Somewhere on the plan there is usually a written dimension, whether it is the overall length or width of the house or an internal room dimension or site boundary dimension. Take a note of this written dimension in millimetres. e.g. in the video, the house length is 23.3 metres long. This converts to 23 300mm.

Step 2: Now measure that same length on your plan with a ruler and record that in millimetres. Here, accuracy is critical so don’t round it up or down, measure to the closest millimetre. eg. as in the video, the house length measurement is 139mm.

Step 3: Take the written dimension in millimetres and divide it by your measurement. e.g.: 23300 divided by 139 = 167.6 (you can round this up to 168) The resultant number will be a percentage. In this case 168%.

Step 4: Photocopy your plan at that percentage. e.g. 168%.

Step 5: Once the plan is photocopied it will now be at 1:100 scale. Getting plans to 1:100 is the most useful scale for house plans and will allow you to measure things accurately even if you don’t have a scale rule. Good luck and have fun! Need more help? Feel free to contact me.