Before installing your new decking, accurately measuring and calculating the total area is essential. Whether you’re planning a DIY project or hiring a professional team, this guide will help you understand how to determine the exact quantity of decking boards needed—saving you time, money, and unnecessary waste.
Step 1: Identify the Shape and Size of Your Decking Area
Start by outlining the shape of the area where you want to install the decking. Common shapes include:
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Rectangle or square
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L-shape
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Circular or irregular shapes
📐 Recommended tools: Tape measure, notepad, pen, ruler, or a drawing app.
Step 2: Measure the Actual Dimensions
For a rectangular or square area:
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Measure the Length (L): The longest side of the decking area (in meters).
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Measure the Width (W): The shorter side perpendicular to the length (in meters).
✅ Example: Length = 5m, Width = 4m
Step 3: Calculate the Total Area
Use the formula:
Area (m²) = Length × Width
🔢 Example:5m × 4m = 20m²
So the total decking area is 20 square meters.
Step 4: Understand Board Sizes and Calculate Quantity
We supply two standard decking lengths:
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4.2m × 140mm (width)
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2.2m × 140mm (width)
To calculate how much area one board covers:
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4.2m board ≈ 0.588m²
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2.2m board ≈ 0.308m²
Now divide your total area by the area of one board:
✅ Example:20m² ÷ 0.588m² ≈ 34 boards (4.2m)
We recommend adding 5–10% extra for offcuts and future maintenance.
Step 5: Calculating Irregular Areas
If your space is L-shaped or non-rectangular, divide it into smaller rectangular sections. Calculate the area of each section separately and then add them together to get the total decking area.
Step 6: Additional Considerations
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Gapping: Leave 3–5mm between boards for drainage and thermal expansion.
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Fascia Boards: If your design includes fascia boards along the edges, measure the perimeter for additional material.
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Joist Spacing: Proper support is critical. Joists should be spaced 350mm to 450mm apart, depending on your chosen decking board.
Final Tip
Still unsure about your measurements or how many boards you need? Feel free to contact our experienced team for advice, product matching, and optional installation service.
📞 Phone: 03-8390 5506
📍 Showroom: 6/39 Eucumbene Drive, Ravenhall, VIC 3023