Moisture-aware gap spacing, layout waste & fastener takeoff
Deck Dimensions
Boards run the full “Length” and are laid side-by-side across the “Width.”
Decking Board Specs
Material & Gap Spacing
Composite boards are near their most contracted when cold, so a colder install needs a wider gap to leave room for summer expansion.
Auto-set from your material choice above — feel free to override to match your manufacturer’s spec sheet.
Layout
Auto-set from your layout above; diagonal cuts always waste more than straight runs.
Joists & Fasteners
Estimated at 2 fasteners per board at every joist crossing, verify against your framing plan and manufacturer spacing guide.
Cost Estimate
Please enter valid deck dimensions first.
Total Decking Boards to Order
–boards
Enter your deck details and calculate to see results.
Fastener & Joist Takeoff
Real-World Purchasing Equivalents
Project Inputs
Estimates are approximate. Gap and layout guidance are general industry rules of thumb always confirm final gap spacing, fastener spacing, and waste factors against your specific decking manufacturer’s installation guide.
QuickTonnage's deck board calculator turns your deck's dimensions into a full materials list in under a minute.
Deck board spacing isn't just a look it's what keeps water moving off your deck instead of sitting in it. Get the gap wrong and boards either buckle from moisture or open up into gaps wide enough to catch a heel.
The right gap comes down to what the board is made of and how wet it is right now:
QuickTonnage's deck board calculator sets a starting gap automatically once you pick your material, so you're not guessing and you can always fine-tune it to match your manufacturer's spec sheet.
It depends on the wood. Wet pressure-treated boards should be installed with no gap at all. Kiln-dried boards need roughly 1/8″ to 3/16″. Composite boards fall in between, depending on installation temperature.
It depends on board width and gap. A 12x12 deck using standard 5.5″ boards with a 1/8″ gap needs roughly 25 to 26 boards, before adding a waste allowance for cuts.
A "2x6" deck board isn't actually 2″ by 6″. Like most dimensional lumber, the actual size is smaller than the name usually 1.5″ by 5.5″. QuickTonnage's calculator uses actual board width, not the nominal size, so your count comes out accurate.
Yes. Diagonal layouts waste more material at every angled cut along the edge, so budget for roughly 15–20% extra compared to a straight layout.
As a rule of thumb, each board gets two fasteners at every joist it crosses. QuickTonnage calculates this automatically from your joist spacing so you know exactly how many screws or hidden clips to buy.