Deck Calculator – How Much Material You’ll Need

Our deck calculator will determine the number of deck boards and fasteners needed for your project. We’ve also provided a formula you can use to calculate the number of boards you need and how to estimate fastener requirements.

deck calculator

To use the deck estimator, enter the length and width of your deck to determine the total square footage. Then enter the length and width of the boards to calculate the board square footage, the number of boards to purchase, and how many fasteners are required.

Decking Calculator

Enter the length, width, and size of decking boards to calculate the number of decking boards and fasteners needed:

To make your own calculations, start by figuring out the square footage of the deck by multiplying the length by the width in feet. Then determine the square footage of each board by figuring the length and width in feet and multiplying those numbers. Divide the deck square footage by the individual deck board square footage for an approximate estimate.

Deck Boards Needed = Deck Square Footage ÷ Individual Board Square Footage

Here’s an example:

  • Your deck measures 16 feet long x 12 feet wide. Multiply 16 x 12 for an area of 192 square feet.
  • Your deck boards measure 12 feet long by 5.5 inches wide. To convert inches to feet, divide by 12.  5.5 ÷ 12 = .459 feet. Then multiply the length by the width. 12 x .459 = 5.51 square feet per board.
  • Divide your total square footage by deck board square footage to determine the needed boards. 192÷.5.51 = 34.85 boards. 

You need about 350 fasteners for every 100 square feet of decking. So, if your deck is about 200 square feet, plan on using 700 fasteners.

How Many Deck Boards Do I Need: Accounting for Deck Board Wastage

The number of deck boards you need depends upon the total square footage of the deck, the size of each board, the gap between the boards, and the deck layout. For example, you’ll experience more board wastage for designs without many angles than for a standard rectangular deck.

Related: How much stain do I need?

Add a 10% waste factor to a standard deck with straight boards. If you’re laying your deck boards on a 45-degree angle or in a herringbone pattern, add a 20-25% waste factor.

To figure waste, multiply the number of boards you need by 1.1 to add an extra 10%. Multiply the number of boards you need by 1.2 to add 20%.

Types of Deck Boards

There are three categories of deck boards: wood, composite, and PVC. If you opt for wood, you can choose between pressure-treated lumber, cedar, Ipe, mahogany, and tigerwood. You can purchase these in many sizes, but the most common is 5.5 inches wide and 12 or 16 feet long.

Composite and PVC decking comes in various styles and colors to mimic natural or painted wood. You can find composite and PVC decking in standard sizes that range from four to six inches wide and 12 to 20 feet long.

Types of Fasteners

Installing a deck requires the use of hundreds of fasteners. There are three main types: nails, screws, and hidden fasteners.

Frequently Asked Questions (FAQ)FAQ

What are plastic deck boards?

Plastic deck boards, also known as PVC deck boards, are made of 100% recycled plastic. They are a maintenance-free option but not the best choice for hot and sunny climates.

How are plastic and composite deck boards different?

Composite decking is a combination of plastic and wood fibers. Plastic deck boards contain plastic only.

How much spacing should you leave between deck boards?

You should leave a ⅛ inch to ¼ inch space between most deck boards. The type of boards, whether they’re dry, and what time of year you’re building factor into spacing decisions.