The Drip Cap

  • A well-built deck is a useful accent for any home.
  • Draw a sketch of your deck and write in the measurements of each side.
  • In order to figure the area of rectangles and squares, multiply the length times the width.
  • If your deck is square or rectangular, you won’t have to add individual areas.

Step 1: Determine Your Deck’s Square Footage

The first step for answering “how to calculate how much decking I need” is to determine your deck’s square footage, or area, by taking the length of your deck times the width (L x W).

EXAMPLE: For a deck that is 16 feet long and 12 feet wide, multiply 16 by 12. This gives you 192 square feet, your deck’s total area.

If your deck has one or more platforms of varying sizes, simply take the area of each platform and add them together for the total area.

Don’t Forget the Stairs

Will your deck have

Don’t Forget the Stairs Will your deck have stairs? You’ll need to multiply the length and width of each step, then add each to your deck’s area to get your total square footage.GET DECK STAIRS IDEAS

Still Visualizing Your Deck Design?

Play around with different deck sizes, shapes, deck board colors, and more with our 3D Deck Design Tool.  



Professional Tips for Planning a Hassle Free Decking Installation

Here’s a professional cheatsheet to plan on the proper amount of decking materials, used by professional contractors and carpenters.  Pro’s make sure there is enough decking materials to get the job done right.  Don’t run short.  Don’t use unusable deck boards. Use the best decking boards, even if you have to trim them up to work best.

How to find the square footage of a board:

For 1 x 6: (5.5 x 12) / 144 = .46

For 1 x 4: (3.5 x 12) / 144 = .29

On this page:

Cost to build a deck – how to use the deck material calculator

  1. Determine the length and width of your deck – you can do this by marking out the corners your designated building area with stakes, putting a string between them, and measuring the length of the line with a measuring tape.

  2. Enter the values into the decking calculator. It will output the square footage of your deck.

  3. Enter the length, width, and price of the decking boards you’ve chosen. The calculator will tell you the square footage of the boards.

  4. Choose the type of fasteners you will use, and the deck cost calculator will output the number of fasteners needed.

  5. Take a look at the number of screws, nails, or hidden clips needed. Find a pack which contains an equal or larger number and enter its price into the deck material calculator. The calculator will estimate the cost of building your deck.

Deck Estimation Tips

Now that you’re a pro at estimating deck boards, consider the following tips as you continue to plan your project.

Order Extra Material

In addition to measuring the deck area, you should also measure how much lumber you’ll need for stairs. It’s a good idea to order 10% additional lumber to account for waste and off-cuts.

Order Extra Fasteners

Also, don’t forget to order enough fasteners for your project, such as hidden fasteners or stainless/coated screws. You will want to order the correct fasteners for the type of decking you’re ordering. Some products, such as composite boards, may require a specific type of hidden fastener or screw.

Different Decking Materials are Sold Differently

While most composite or softwood decking is sold by the board, some hardwood or exotic options are sold by the board foot. If that’s the case, use a board footage calculator to estimate how much lumber you’ll need for the project.

Estimate the Total Cost

Before you start your project, you should refer to our deck cost calculator to get an idea of how much it costs to build a deck and what options are available.

Get Professional Estimates in Addition to Research

We have several great resources to help with your deck project. Get a free estimate from a local contractor if you’re interested in having someone else quote the project. Estimate how much concrete you need for your posts with our concrete hole calculator.

How to find the number of hidden deck fasteners you need for 16” O. C. framing:

Formula: Multiply .75 x linear foot = number of hidden deck fasteners


  • Take .75 and multiply by 729 linear feet = 547 hidden fasteners
  • Now add 10%.
  • Order 602 hidden deck fasteners.

How do you calculate decking?

Decking calculator equation

  1. Step 1: Calculate the surface area of your decking. Multiple the length (L) of your decking area by the width (W).
  2. Step 2: Calculate the coverage of your deck boards. Add the deck board width (W) to the Expansion Gap Length (EGL).
  3. Step 3: Calculate the number of boards required.

Step 6: Account for Mishaps, Waste, Off Cuts

When asking yourself “how to calculate how much decking I need,” it’s best to add a few extra boards than you think you’ll want on-hand. Slip-ups while cutting, fasteners placed at the wrong angle, and other issues are sure to crop up, even for the most skilled DIYer.

To be safe, add at least a 10% to 15% scrap rate to the number of boards you need to cover mishaps, waste, and off cuts.

EXAMPLE: Step 5 confirmed you need 27 deck boards for the build. To add 10%, multiply 27 by 1.1 to get 29.7 — best to round up to 30 boards. For a little extra cushion, add 15% by multiplying 27 by 1.15 to get 31.05 and round up to 32 boards.

If you’re laying your boards diagonally, or are planning a more elaborate pattern like herringbone, add 10% to 15% more to the normal scrap rate.

MEASURE TWICE, CUT ONCE. Keep a list of what influencing factors matter to you most; this will help you align your creativity to you and your family’s needs.


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