Deck and fence takeoff
The list you hand across the counter. Board gaps are part of the coverage and lengths are chosen by what divides into your run, which is where most takeoffs done in your head go wrong.
Joists run the other way, so this decides both counts
On centre
Advanced settings3/16" gap · 10% waste
= 0.188"
Culls, cuts and the one you drop
192 sq ft of deck
29× 16 ft boards
Rows of decking
26
Joists
13
Screws
744
Each board covers 5 11/16" once the 3/16" gap is counted, so 26 rows span the deck. A 16 ft board yields 1 row, leaving 0% offcut.
Order this
- Decking — 5/4 x 6 (5 1/2" wide)416 linear feet laid, before waste
- 29 × 16 ft
- Joists16" on centre
- 13 × 12.0 ft
- Deck screwsTwo per board per joist, plus a tenth for the ones you lose
- 744
- Last row widthNeeds ripping
- 1 13/16"
Where to buy this
- 29 × 5/4 x 6 (5 1/2" wide)Home DepotLowe's
- 13 joists at 12.0 ftHome DepotLowe's
- 744 deck screwsHome DepotLowe's
Joist and beam sizes depend on your span and species — this links to the material, not a size we have worked out for you.
Plain search links, nothing sponsored. Prices and stock are the shop's, and a local lumberyard will usually beat both on solid stock.
Worth knowing
The last board has to be ripped to 1.81". Rip it off the last two rows instead of one if that leaves an awkward sliver — two nearly-full boards look deliberate and one thin one does not.
Worked example: a 16 × 12 ft deck
A 16 × 12 ft deck is 192 sq ft. In 5/4x6 boards (5 1/2" wide) with 3/16" gaps it takes 26 rows of decking, and the last row is ripped to 1 13/16".
With 10% waste that is 29 boards 16 ft long, 416 linear feet in all.
Underneath: 13 joists at 16" on centre, 156 linear feet of joist, and about 744 deck screws.
- Deck boards
- 29 × 16 ft
- Rows
- 26
- Last row
- 1 13/16"
- Joists
- 13
- Screws
- 744
These are the figures the calculator above opens on. Change any field and it works the same problem for your numbers.
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About decks and fences
- What gap should I leave between deck boards?
- 3/16" for kiln-dried or composite boards — the figure composite makers publish and the one this site's deck chart works to — and none at all for pressure-treated stock installed wet. Wet treated lumber shrinks as it dries and opens its own gaps — butt those tight and you end up with the spacing you wanted. Do the same with dry boards and they have nowhere to expand, which is how a deck buckles.
- How many screws will I need for a deck?
- Two per board at every joist it crosses. A 16 by 12 foot deck with joists at 16" on centre works out to roughly 700 screws, and it is worth adding ten percent for the ones that snap, cam out, or roll under the deck. Hidden fasteners change the maths completely — count those by the manufacturer's coverage per box instead.
- How deep should fence posts go?
- A third of the height above ground, and never less than two feet. A six foot fence therefore wants two feet in the ground and an eight foot post. The fence is a sail; what holds it up in a gale is the depth of the post and the width of the concrete around it, not the fasteners.
- How much concrete does a fence post take?
- Just over two 60 lb bags for a 4x4 in a 10" hole two feet deep — so buy three and have some left. The usable volume is the hole less the post itself, which is why the calculator subtracts it rather than treating the hole as solid concrete: the post takes about a fifth of a 10" hole, which is most of half a bag. Gate posts want a bigger hole and more concrete than run posts — they carry a swinging load every day for years.
- How far apart should deck joists and fence posts be?
- Joists at 16" on centre for 5/4 decking, and up to 24" for 2x stock — a decking board that spans too far feels springy underfoot long before it is unsafe. Fence posts are usually 6 to 8 feet apart; this calculator divides the run evenly at or under your target so you do not finish with a short bay at one end.
You might also need
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- Floor joist spansThe 2021 IRC's maximum span for a 2x6 to 2x12 floor joist by species, grade and spacing, and what would reach when yours falls short.
- Pergola calculatorPosts, beams, rafters and top slats for a pergola from its footprint and the spacings you choose, evenly laid out and turned into boards to buy.