Deck Joist Quantity Calculator
Estimate deck joist count, full stock boards, rim boards, hangers, total lumber length and material cost from deck dimensions and spacing.
Default project preview
14 boards
Joist count
11
Joist stock boards
11
Rim boards
2
Joist hangers
22
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Joist lines = round up (deck width ÷ spacing) + one. Each joist and rim line is converted to full stock boards, then the extra-board allowance is applied.
BuildMeter Guides
Understand the measurements and assumptions
Use these visible reference guides before changing project inputs or planning allowances.
FAQ
Deck Joist Quantity Calculator questions
Why add one joist after dividing by spacing?+
Spacing counts gaps between joist centerlines, so a run with several spaces has one more joist line.
Can shorter boards be joined to make a joist?+
Splices require proper support and approved detailing; the stock calculation does not design splice locations.
Does this determine joist size?+
No. Member size and spacing must be selected from the project design and applicable requirements.