Calculate how many decking boards you need, with a 10% allowance for cuts and staggered joints included automatically.
Enter the deck's length and width (or total area). We work out the board count from real UK board sizes — joists, posts and fixings are separate, so add those to your project board as custom items.
01 — The Calculator
Pick a material, pace out your plot, and the value engine prices every way to fill it — hippo bags, dumpy bags or handy sacks.
Enter dimensions to calculate.
Area
0.0 m²
Boards needed
0 boards
Wastage
+10%
Coverage
0.0 m²
Enter your plot dimensions and the value engine will price the cheapest way to cover it.
Worked example: 20m² deck
A 5m × 4m deck is 20m²; with 10% wastage you'll need boards covering 22m². The calculator prices the exact count and shows the total, so there are no surprises at the merchant.
10% covers end cuts and staggered joints. Diagonal layouts need around 15%.
Garden Calculator — Project
My garden project · 20 September 2026
| Item | Qty | Each | Total |
|---|---|---|---|
| Estimated total | £0.00 | ||
Prices from the Garden Calculator sample trade catalogue — confirm with your merchant before ordering.