Choosing composite decking? Enter the deck size and the board price. You get the boards, hidden clips and board cost, with extra for cuts included.
Your shopping list
29Composite boards to buy
372Hidden clips
1,740.00Board cost
- Joists13
- Rows of boards26
Prices are the numbers you type in, so use one currency. Clips are one per board at each joist. Extra of 10% is included.
How to use the Composite Decking Calculator
- Enter the deck length and width.
- Pick the board width, board length and joist spacing from your brand guide.
- Type the price of one board and read the list.
The math behind it
Rows = deck width x 12 / (board width + 1/8 in), rounded up
Boards = rows x deck length / board length, rounded up
Clips = rows x joists x (1 + extra %)
Cost = boards x price per board
A worked example
What we typed in
- Deck length: 20 ft
- Deck width: 14 ft
- Board width: 5.5 in wide (common)
- Board length: 16 ft
- Joist spacing: 16 in apart
- Price per board: 72.00
- Extra for mistakes and cuts: 10%
What we got
- Composite boards to buy: 42
- Hidden clips: 528
- Board cost: 3,024.00
- Joists: 16
- Rows of boards: 30
Tips from the job site
- Composite boards sag if joists are too far apart. Follow the brand span chart.
- Hidden clips cost extra but leave a clean surface with no screws.
Common questions
How many composite boards do I need?
Count the rows across the width, then the boards in each row, and add 10% for cuts.
How far apart should joists be for composite decking?
Most brands want 12 to 16 in. Check the install guide for your board.
See all Deck Calculators.