Use this free decking calculator to plan a home-improvement or DIY project from the measurements and product information you already have.
HomeCalc shows the formula behind the result and keeps product-dependent assumptions editable where possible, so the calculator can match the material, package or supplier you actually plan to use.
🧮 Quick answer
Enter deck size, board width, board length, board gap and waste allowance. HomeCalc estimates the surface-board quantity only.
Enter deck size, board width, board length, board gap and waste allowance. HomeCalc estimates the surface-board quantity only.
FREE DECKING ESTIMATOR
Decking Calculator: Boards & Linear Feet Needed
Estimate decking boards and linear feet for a rectangular deck surface.
Estimated result
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Planning estimate: real material requirements can vary with measurements, cuts, waste,
product yield, installation method and supplier packaging. Check the manufacturer or supplier information before buying.
Estimate surface decking from effective board width
Deck boards cover the surface in repeated rows. HomeCalc combines the board face width with the chosen gap, calculates how many rows fit across the deck and converts the requirement into linear feet and whole boards.
HomeCalc formula
deck area ÷ effective board width = linear feet of decking
What to check before using the result
- Use the actual finished board width rather than the nominal lumber name.
- Include the installation gap because it affects the number of rows.
- Board direction changes which deck dimension controls row count and board length.
- This is a surface-board estimate; framing, stairs, fascia, railing and hardware are separate.
Board width plus gap controls how many rows you need
A small gap repeated across an entire deck adds measurable width. Ignoring it can slightly overestimate rows, while using nominal rather than actual board width can produce a larger error.
A small gap repeated across an entire deck adds measurable width. Ignoring it can slightly overestimate rows, while using nominal rather than actual board width can produce a larger error.
Frequently asked questions
Does this calculate joists and framing?
No. It is intended for the decking surface boards and related linear footage.
Should I use nominal or actual board width?
Use the actual face width of the decking product.
Why add a waste allowance?
Cuts, defects, end trimming and board selection can require more stock than the exact surface calculation.