Decks are wonderful outdoor living spaces. Building one around your home can make spending time with your family more enjoyable and increase your property value. When building a deck, preparation is key. To save yourself many trips back and forth to the hardware store, use the size of your deck to calculate the number of screws you will need.
Things You'll Need
 Notepad
 Pencil
 Calculator
How to Calculate the Number of Screws Required for a Deck

Measure the your deck. You need to know the length and width of the entire deck to determine the total square footage. For example: 24 feet times 15 feet is 360 square feet. Write this number down.

Measure the joist spacing. A joist is the skeleton bones of the deck that hold the planks in place. Assume your joists are 15 inches apart. Divide this by the width of your deck to determine how many joists. In this case, that would be 12. 12 joists = 15 feet (12 inches per foot) / 15 inches per joist.

Measure the length and width of each deck board. You may be using 12 inch x 5.5 inch planks. Calculate how many deck board are required. In this example: 24 feet x 12 inches per foot / 12 inches per board = 24 boards.

Determine how many screws you want at each joist intersection. You should have at least two, but you may want more depending on your design width of each board. For this example, assume two screw per joist intersection is adequate for a board width of 5.5 inches.

Calculate the number of screws estimated: Two screw per joist x number of joists x number of deck boards. For this example: 2 screws per joist x 12 joists x 24 deck boards = 576 screws.
Tips & Warnings
 It is best to draw your plan out ahead of time with the measurements and any gaps you will have between the decks. This way you can see what your goal is and make sure you are purchasing all the right materials in advance. There are many great calculators on the Internet that help determine this more exactly based on the type of materials you are using, the thickness of each board and any shape alterations on your deck.