How this deck lumber calculator works
The calculator converts deck width to inches, divides it by one board face width plus one gap, and rounds up to a whole board. It then multiplies the board count by deck length to show total linear footage. Deck surface is length multiplied by width.
This estimate assumes boards run the full deck length on a simple rectangle. It does not calculate joists, beams, posts, fasteners, picture framing, stairs, diagonal layouts, or waste.
Plan board lengths before ordering
A result of 16-foot boards does not guarantee that 16-foot stock is the best purchase. Check what lengths your supplier carries, where butt joints will land, and whether you want staggered joints. For a deck wider than the stock boards you choose, calculate each run and joint pattern separately.
Use the installed board width
Enter the face width you expect after installation. Nominal lumber size and actual face width can differ, and decking products can vary by manufacturer. The planned gap should also match the product instructions and the conditions where the deck will be installed.
Before building
- Measure the finished deck surface, not the overall property space.
- Separate rectangular sections, bump-outs, and stair treads into their own estimates.
- Keep a separate list for framing lumber and structural hardware.
- Confirm structural requirements, permits, and local code with the appropriate professional or authority.
Need lumber volume or cost?
Use the board foot calculator when your lumber quote is priced by board foot. It totals thickness, width, length, quantity, and an optional per-board-foot price.
Deck board calculator and deck board estimator
This deck board calculator is a deck board estimator for a rectangular surface. Use the deck lumber calculator above with your installed face width and deck dimensions; the deck lumber estimator reports surface boards and linear feet using the method already described here.
Deck board spacing calculator
The gap input lets you compare the material count for a spacing you have chosen. It does not select an installation gap. Use the installation instructions for your exact product and conditions.
Trex deck board calculator and composite deck board calculator
If you are looking for a Trex deck board calculator or a composite deck board calculator, enter the actual installed face width and the gap specified for your product. This independent surface estimate does not check a manufacturer's fastening, end-gap, or framing requirements. It is not affiliated with Trex.
Deck lumber questions
Does the board count include extra material?
No. Add your own allowance for cuts, sorting, defects, and layout changes after you have reviewed your plan.
Can I use this for diagonal decking?
Not as a final order estimate. Diagonal layouts require longer board runs and more trimming, so calculate from a layout-specific material plan.
Does this calculate framing lumber?
No. It estimates surface deck boards only. Joists, beams, posts, blocking, and hardware need a separate structural plan.