How to Measure a Room

Made to Measure: How to measure a room

Most tradespeople who work in finishing trades including tiling, decorating and plastering will calculate the price of work by the size of the room or wall to be worked on.

While many people are comfortable gauging sizes roughly, many struggle to estimate the meterage with a reasonable degree of accuracy. This ability is handy as a rough idea allows for an estimated tile, paint or material cost to be made before a tradesperson arrives.

So how do you measure a room? An inch perfect measurement is difficult but for a ballpark idea there are some simple measurements you can try.

If you wish to measure the walls in a room - try this technique:

  1. The box room

    Measure the height of the room floor to ceiling; the average height is 2.4 metres so let's use that to start.

    An image of a floor to ceiling measurment The average height of most ceilings is 2.4m

    We can then measure two walls, in this example 3.15m and 1.95m.

    An image of 2 walls being measured

    Provided the room is more or less symmetrical, we can calculate the wall space of the room:

    • 2 walls of 3.15 metres plus 2 walls of 1.95 metres
    • (2 x 3.15) + (2 x 1.95)
    • 6.3 + 3.9 = 10.2

    We can also check this manually. Measure all the way around the room by starting in any corner and working your way around the walls and finishing in the same corner – you should end up with 10.2 m.

    With a calculator, multiply 2.4 by 10.2 and you get 24.48m2 (you could potentially round this to 24.5m2 for ease).

    This would be the exact meterage of the room you are standing in - if it was a bare box.

  2. The actual room

    There are parts which obviously do not need tiling or painting such as doorways, windows, baths etc. These other parts of the room need to be factored into your calculation.

    An image of windows and doors blocked out for measurement

    Using the same method, measure the height and width of the door (not pictured):

    • 1.1 metres wide by 2.1 metres high
    • 1.1 x 2.1 = 2.31m2

    Do the same for the French doors:

    An image of French doors being measured
    • 1.5 metres wide by 2.1 metres high
    • 1.5 x 2.5 = 3.75m2

    And the same for the window:

    An image of a window being measured
    • 1.2 metres wide by 0.8 metres high
    • 1.2 x 0.8 = 0.96m2

    Taking all aspects of the room we have

    • Four walls measuring - 24.48m2
    • One door - 2.31m2
    • One set of French doors - 3.75m2
    • One window - 0.96m2

    By subtracting the elements of the room from the total wall measurement, you are left with a rough meterage size of 17.46m2.

    When consulting with a Local Hero (or other tradesperson), you can round to 17.5m2 or even 18m2.

    Use these measurements when getting costs for materials and compare these measurements and costs to the quotes your tradesperson provides. While it’s unlikely they will match exactly, having a rough estimate helps make sure you’re not paying over the odds.

    Tip: For floors simply do the same, width x length equals square meterage.