Deck Calculator

Enter your deck size and get the boards, joists and screws you need to buy.

Building a deck starts with the same question every time: how many boards do I actually need? Deck Calculator turns your deck size into a full material list — deck boards, joists, beams, posts and screws — and draws the deck from above so you can see the layout before you buy anything.

HOW IT WORKS
Type the width and length of your deck. Choose a board size, joist spacing and board direction with a tap. The plan view redraws instantly and the material list updates with it. No forms to submit, no waiting.

WHAT YOU GET
• Deck boards — how many pieces, based on board width and the gap between boards
• Joists — count and length for the spacing you choose (12", 16" or 24" on center)
• Rim joists and beams — the frame around and under the deck
• Posts — added when you enter a deck height, with the length including the buried part
• Deck screws — estimated by weight so you can grab the right box
• Total area in ft² — handy when you compare quotes

FEATURES
• Live plan view — boards, joists and the frame redraw as you change anything
• Board direction — flip between running across the width or along the length and watch the layout rotate
• Seam warning — if a row is longer than one board, the app tells you how many pieces per row so you can plan the seams
• Waste allowance — add 5% or 10% for cuts and defects, or keep the count exact
• Cost estimate — enter your local unit prices and see the running total
• Copy the list — one tap copies everything as text, ready to read at the store or paste into a message
• Save your decks — keep several layouts and reload them while comparing options
• Works offline — no account, no sign-up, nothing to load

BUILT FOR
• Homeowners planning a backyard deck
• Deck builders and landscapers pricing a job
• Anyone estimating lumber before a trip to the yard

NOTES ON ACCURACY
Joist count assumes joists at the spacing you pick plus one at the end. Beams and posts use a simplified layout, and board counts assume standard stock lengths. The numbers are an estimate to help you plan and shop — always confirm framing, footings and spans against your local building code and the conditions on your site before you order or build.