Deck Screw & Fastener Calculator
Quick answer: About 3.5 deck screws per square foot — two at every joist on 5½ in boards with joists 16 in on centre, plus 10% for ends and butt joints. A 12 × 16 deck (192 sq ft) takes about 670 screws: 7.5 lb or two 5 lb boxes of 2½ in #9 deck screws, roughly $40. At 12 in joist spacing it is 4.6 per sq ft.
Fastener counts are easy to underestimate and unpleasant to run short of halfway through a deck. The number depends on the joist spacing, the board length and whether you are face-screwing or using hidden clips. This counts every screw or hidden clip from your deck size, joist spacing and board width, then converts it into pounds, boxes and cost so you buy the right amount the first time.
Built and maintained by DixonAppStudio LLC · How the figures are worked out · Report an error
What you'll need
As an Amazon Associate I earn from qualifying purchases.
ManCoda Hidden Deck Fasteners for Composite Decking Board, Universal Hidden Fasteners with Stainless Steel Screws, Composite Decking Clips for Wood Deck Framing, 900 Pack for 500 SQ.FT.
$239.00
Check price on Amazon
Deck Screws 2-1/2 Inch, #10 x 2-1/2, 5lb, 385Pcs Rust Resistant, Brown Epoxy Coated, Outdoor Screws, Torx/Star Drive, T25 Bit
$24.99
Check price on Amazon
SVLING 340Pcs Multi-Purpose Wood Deck Screw Kit,#8#9 Bugle Head for Interior and Exterior Use,Star Drive Torx Golden Coated with T15/T25 Bit
$23.99
Check price on Amazon
DEWALT Screwdriver Bit Set, 40 Pcs. Impact Ready, FlexTorq Impact Driver Bit Set with Storage Case (DWA2T40IR)
Limited time dealSave 17%
$17.98Typical price:: $21.57
Prices and savings as of Oct 25, 2026, 4:32 AM UTC. Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
Shopping for someone? See our backyard gift guide for deck builders & DIYers.
Choosing the screw? See the best deck screws and fasteners.
Clips, edge screws or plugs? See our hidden deck fastener buying guide — counts from this calculator.
How many deck screws per square foot?
Every board gets two screws at every joist it crosses. With 5½ inch boards, a 3/16 inch gap and joists at 16 inches on centre, that works out to about 3.2 screws per square foot, or 3.5 with a 10% allowance for butt joints, ends and drops. Change the spacing or board width and the number moves quickly:
| Joist spacing | 5½ in boards | 3½ in boards | 200 sq ft deck (5½ in) |
|---|---|---|---|
| 12 in on centre | 4.6 per sq ft | 7.2 per sq ft | ~930 screws |
| 16 in on centre | 3.5 per sq ft | 5.4 per sq ft | ~700 screws |
| 24 in on centre | 2.3 per sq ft | 3.6 per sq ft | ~470 screws |
How many screws in a box?
The standard 2½ inch #9 deck screw runs about 85–95 per pound, so a 5 lb box holds roughly 425–475 screws and a 25 lb bucket about 2,200. Three inch screws, used for 2× decking, are closer to 70–75 per pound. Buy by the pound with a spare box — returning an unopened one is easier than a second trip with four boards to go.
Deck screws by deck size
At 3.5 screws per square foot (5½ inch boards, 16 inch joist spacing, 10% allowance) and about 90 of the 2½ inch screws to the pound, the order for common deck sizes is:
| Deck | Area | Screws | Weight | 5 lb boxes |
|---|---|---|---|---|
| 10 × 10 | 100 sq ft | ~350 | ~3.9 lb | 1 |
| 12 × 12 | 144 sq ft | ~505 | ~5.6 lb | 2 |
| 12 × 16 | 192 sq ft | ~670 | ~7.5 lb | 2 |
| 16 × 20 | 320 sq ft | ~1,120 | ~12.4 lb | 3 |
| 20 × 20 | 400 sq ft | ~1,400 | ~15.6 lb | 4 (or one 25 lb bucket) |
That is roughly 0.04 lb of screws per square foot. For other sizes, get the area from the deck square footage calculator and enter it above.
Hidden clips instead of screws
Hidden clip systems use one clip per board per joist crossing — about 1.7 per square foot at 16 inch spacing — and typical kits hold 90 clips for about 50 square feet. They cost around $0.50–$0.60 per clip against $0.05–$0.07 per screw, and they are slower to install, but they leave a clean surface with no screw heads to hold water, which matters most on composite. The first and last boards and any picture-frame border are still face-screwed.
Choosing the right screw
- Pressure-treated lumber: coated screws rated for ACQ/CA/MCA treatment, or stainless.
- Cedar and redwood: stainless to avoid black tannin staining around each head.
- Composite and PVC: the board maker's colour-matched screws — others can void the warranty.
- Within sight of salt water: 316 stainless for everything.
Structural fasteners are a separate list: joist hangers with their specified nails, ledger lags or through-bolts (see the ledger fastener calculator), post bases and caps. Never use deck screws in hangers — they have no rated shear capacity. For the board count that drives all of this, use the deck board calculator.
Get the Smart Decking Calculator app for Android
Estimate decks on the go, save projects, and share them with contractors.
Building something else? Try our sister calculators
Smart Fencing Calculator
Estimate fence cost by material and linear footage.
Smart Roofing Calculator
Free roof replacement cost estimates by material.
Fence Calculator
Android app — posts, pickets, panels and fence cost.
Gravel & Stone Calculator
Android app — gravel under the deck and footings, in tons and yards.
Roofing Calculator
Android app — roof squares, shingles and covered-deck roofs.
Drywall Calculator
Android app — drywall sheets, mud, and tape estimates.
Frequently asked questions
- How many deck screws per square foot?
- About 3.2 screws per square foot, or 3.5 with a 10% allowance, for 5½ inch boards on joists 16 inches on centre with two screws per joist. At 12 inch spacing it is 4.6 per square foot and at 24 inches 2.3.
- How many deck screws do I need for a 12x16 deck?
- About 670 screws for 192 square feet at 16 inch joist spacing: roughly 7.5 lb, or two 5 lb boxes of 2½ inch #9 deck screws, at about $40. A 10x10 deck needs about 350 and a 16x20 about 1,120.
- How many deck screws are in a pound?
- About 85 to 95 of the standard 2½ inch #9 deck screw, so a 5 lb box holds roughly 425 to 475 and a 25 lb bucket about 2,200. Three inch screws for 2× decking run 70 to 75 per pound.
- How many screws do I need for a deck?
- Two screws per board at every joist crossing. At 16 inches on centre, a 16 ft board crosses 13 joists, so 26 screws a board. A 16 by 12 ft deck with 26 rows works out around 676 screws, or roughly 3.5 screws per square foot. Buy by the pound with 10 percent spare — the last thing you want is a second trip with four boards to go.
- Are hidden fasteners better than face screwing?
- They look considerably better and they leave no screw heads to collect water, which matters on composite. The costs are money and time: clips run around $1.60 to $2.80 per square foot against roughly half that for screws, and they are slower to install. They also make a single damaged board much easier to replace later, which face screwing does not.
- What screws should I use for pressure-treated decking?
- Screws rated for contact with modern preservative treatments — stainless steel, or a coated deck screw whose manufacturer lists it for ACQ, CA or MCA-treated lumber. Plain zinc-plated screws corrode in treated wood, sometimes within a couple of seasons, and the streaks they leave are permanent. Stainless is required near salt water.
- Do I need joist hangers on a deck?
- Yes, wherever a joist ends against a ledger or a rim rather than bearing on top of a beam. Use hangers rated for exterior use and fill every nail hole with the hanger nails the manufacturer specifies — not deck screws, which have no rated shear capacity. Hangers left half-nailed carry a fraction of their rated load.
- How many deck screws are in a 5 lb or 25 lb box?
- Roughly 425 to 475 of the common 2 1/2 inch #9 deck screws in a 5 lb box, or about 85 to 95 per pound, so a 25 lb bucket holds about 2,100 to 2,400. Longer 3 inch screws come in around 70 to 75 per pound — about 1,750 to 1,900 in 25 lb. A 200 square foot deck needs about 700 screws, so two 5 lb boxes; a 25 lb bucket covers roughly 600 to 680 square feet at 3.5 screws per square foot.
- How many hidden deck clips do I need?
- One clip per board per joist crossing — about 1.7 clips per square foot at 16 inch joist spacing with 5 1/2 inch boards, including a small allowance. Most clip kits hold 90 clips and cover about 50 square feet. The first and last boards and any border are face-screwed, so buy a small box of colour-matched screws as well.
- How many screws per deck board?
- Two at every joist the board crosses. A 16 ft board on joists at 16 inches on centre crosses 13 joists, so it takes 26 screws; at 12 inch spacing it crosses 17 joists and takes 34. Keep screws about 3/4 inch from the board edge and pre-drill near the ends to stop splitting.
- How many pounds of deck screws do I need per square foot?
- About 0.04 lb per square foot, or 4 lb per 100 square feet, for 2 1/2 inch screws at roughly 90 per pound and 3.5 screws per square foot. A 200 square foot deck needs about 8 lb, so two 5 lb boxes. Use 3 inch screws (about 70 to 75 per pound) and it rises to roughly 5 lb per 100 square feet.
