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How to calculate square metres

Person measuring timber pieces with measuring tape.

Overview

Calculating the size of a space is an important step in any construction or DIY project. Learn how to calculate squares metres with this guide from Bunnings.

Steps

1Break down your area for measuring

When measuring large areas, breaking it down into smaller sections will make it easier. For this project, we have broken our space into two rectangles that will be measured separately then added together. Measure the first of these rectangles, starting with the width, followed by the length, and repeat the process on the second rectangle. Mark these measurements in your notebook.

Person measuring timber pieces with measuring tape.

2Round up your measurements

It's always a good idea to round up your measurements. Once you have finished calculating all the measurements, add a 10 per cent contingency on top to make sure you have more than enough materials for the job you're about to undertake. 

Person using notepad to make calculations.

3Use your measurements to calculate the area

To calculate the area of each of your rectangles, multiply the length by the width. For this project, that sum is 3m x 1m = 3m² for the first rectangle, and 6 x 2 = 12m² for the second. Because we are measuring the whole deck, we add these numbers together to get the final area measurement. So that sum is 3m + 12m = 15m². Make sure to add the 10 per cent contingency to this final sum. You can do this by multiplying the total and adding this to amount to the total. So 15m x 0.1 = 1.5m², therefore the total area is 15m + 1.5m = 16.5m².

Notepad, calculator and measuring tape.
Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer.