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Whether you're planning a renovation, buying materials, or figuring out the size of a space, knowing how to calculate square metres is an essential skill. It helps you estimate costs, plan layouts, and make sure you buy just the right amount of material—no more, no less.
This guide will show you how to calculate square metres for any room or surface, taking the guesswork out of your next D.I.Y. project.
Safety tip: Always wear the appropriate safety equipment (safety glasses, gloves, ear muffs and a mask, for example) and always follow the instructions for the product or equipment.
Measure the length and width
Let’s begin with the simplest scenario: a rectangular space. Use your measuring tape to measure the length of the space in metres. Place the tape from one end to the other, ensuring the tape is straight for an accurate measurement
Tip: Measure along the ground, as measuring at an angle may give inaccurate results.
Next, measure the width of the space in metres. Again, ensure the tape measure is straight and flat to get an accurate measurement.
Multiply the length by the width to get the total square metre size. For example: 5 metres × 4 metres = 20 square metres. It’s as simple as that! Knowing this measurement is particularly helpful when planning to buy flooring, paint, or even turf.
Break down the area
If the area you’re measuring has an irregular shape, such as an L-shaped room or a garden with a nook, break it down into smaller rectangular sections. Measure each section individually
Tip: It may help to sketch the area and divide it visually into rectangles before measuring.
Measure the length and width of each rectangular section separately. Record the measurements in metres.
Calculate the square metres for each section
Calculate the square metre size for each section by multiplying length by width, just as you would for a standard rectangle. For example: The main section is 3 metres × 5 metres = 15 square metres and the additional section is 2 metres × 2.5 metres = 5 square metres.
Add them together to get the total area. For example: 15 square metres + 5 square metres = 20 square metres.
For curved or uniquely shaped spaces, like garden beds or patios, it’s often easiest to approximate. Imagine the shape as a rectangle that covers the largest part of the area. Measure and calculate it as if it were a rectangle. While not 100% precise, this method will give you a close enough estimate for most D.I.Y. projects.
Tip: If precision is important, consider breaking the complex shape into smaller rectangles or use a flexible measuring tape to better follow the curves.
If your measurements are in centimetres, convert them to metres before calculating. Simply divide the measurement in centimetres by 100. For example: 450 cm = 4.5 metres.
Learn how to lay floor tiles.
Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. 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 or visit our Health & Safety page.
When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.
