How Much Decking Do I Need? A Simple Guide for Your Next Project
How Much Decking Do I Need? A Simple Guide for Your Next Project
One of the most common questions we get from customers planning a new deck is simply: "how much timber do I actually need?" Getting this right up front saves you a second trip to the yard and helps you budget accurately. Here's how to work it out in a few easy steps — or skip straight to our free Decking Calculator and let it do the maths for you.
Step 1: Measure Your Deck Area
Measure the length and width of your deck in metres and multiply them together to get your total area in square metres (m²). For an irregularly shaped deck, break it into smaller rectangles, calculate each separately, and add them together.
Step 2: Choose Your Board Width
Merbau decking is available in 90mm and 140mm widths. Wider 140mm boards cover your deck area faster (fewer boards, fewer joins) and give a bolder, more contemporary look. Narrower 90mm boards are a popular classic choice and can suit smaller decks or tighter budgets.
Step 3: Account for the Gap Between Boards
A small gap (typically 3–5mm) is left between each board for drainage and to allow the timber to expand and contract naturally. This slightly increases the effective width each board covers — our calculator factors this in automatically.
Step 4: Add a Waste Allowance
It's standard practice to add 10% to your total lineal metres to allow for cutting, trimming to length, and any mistakes along the way. Larger or more complex deck shapes may need a bit more.
Step 5: Work Out Your Board Count and Fixings
Once you know your total lineal metres required, divide by your chosen board length (we stock lengths from 2.4m up to 6.0m) to get the number of boards to order. You'll also need two decking screws per board at every joist, so the total screw count depends on your joist spacing (450mm centres is standard for residential decks).
Let the Calculator Do the Work
Rather than running these numbers by hand, our free Merbau Decking Calculator takes your deck length, width, board width and length, and instantly gives you the area, lineal metres (including waste), board count, and approximate screw count — all in one place.
Once you've got your numbers, our team can help confirm the exact order and answer any questions about board selection, finishes, or delivery — just get in touch.