About 4 deck screws per square foot, roughly 400 per 100 sq ft on 16" joists with 5-1/2" boards. The deck screw calculator formula is boards x joists crossed x 2, plus 10% for waste. Deck board screws only; ledger, beams, joist hangers, posts and railings take structural fasteners.
We've been building decks for over 28 years, for homes and for businesses, and ordering the screws for every one of them. This post is the working behind our Screw Calculator page: where the numbers come from and which box to order.
| Deck size | Board width | Joist spacing | Deck board screws needed | Screws to buy (+10%) | Eagle Claw pack to buy |
|---|---|---|---|---|---|
| Per square foot | 5-1/2" | 16" | 4 | 5 | 100 pack covers about 20 sq ft, 350 pack about 70, 1000 pack about 200 |
| Per square meter | 5-1/2" | 16" | 43 | 48 | 100 pack covers about 2 m², 350 pack about 7, 1000 pack about 20 |
| 10 x 10 (100 sq ft) | 5-1/2" | 16" | 396 | 436 | 350 pack + 100 pack |
| 10 x 10 | 5-1/2" | 12" | 484 | 533 | 1000 pack |
| 10 x 10 | 5-1/2" | 24" | 264 | 291 | 350 pack |
| 10 x 10 | 3-1/2" (nominal 4") | 16" | 612 | 674 | 1000 pack |
| 10 x 10 | over 6" (3 screws per crossing) | 16" | 459 | 505 | 1000 pack |
| 12 x 12 (144 sq ft) | 5-1/2" | 16" | 520 | 572 | 1000 pack |
| 12 x 16 (192 sq ft) | 5-1/2" | 16" | 676 | 744 | 1000 pack |
| 16 x 20 (320 sq ft) | 5-1/2" | 16" | 1,120 | 1,232 | 1000 pack + 350 pack |
| 20 x 20 (400 sq ft) | 5-1/2" | 16" | 1,376 | 1,514 | 1000 pack + 350 pack + 350 pack |
| 1,000 sq ft (25 x 40) | 5-1/2" | 16" | 3,348 | 3,683 | 4 x 1000 pack |
| One 8 ft board | 5-1/2" | 16" | 14 | 16 | n/a |
| One 12 ft board | 5-1/2" | 16" | 20 | 22 | n/a |
| One 16 ft board | 5-1/2" | 16" | 26 | 29 | n/a |
Key Takeaways (TL;DR)
- Use about 4 screws per square foot, or 43 per square meter, if you're on 16" joists with 5-1/2" boards.
- Use two screws per board at every joist if your boards are 5-1/2" wide, and three only if they're over 6".
- Use the boards x joists x 2 math if your deck is under about 300 sq ft, where the 350 per 100 sq ft rule runs low.
- Use a by-count pack if you want the box to match the table, since a 5 lb box is an approximate count.
- Use 10% extra if you're buying stainless, because no local store carries a matching #10 304 or 316.
Not sure yet? Try before you buy.
Before you order 400 or 4,000 deck screws, drive a few of our 304 and 316 stainless steel deck screws into an offcut of your own boards. Check the length and the Torx drive in your pressure treated pine, cedar or hardwood, then order the full count once.
How Many Deck Screws Do I Need Per Square Foot?
You need about 4 deck screws per square foot at 16" joists with 5-1/2" boards, before waste, or about 43 per square meter. With 10% added, order 5 per square foot or 48 per square meter.
The formula is boards x joists crossed x 2. A 10 x 10 worked through:
- Boards: 120" of depth over a 5.625" pitch (5-1/2" board plus a 1/8" gap) is 21.3, so 22 boards.
- Joists crossed: 120" over 16" is 7.5 bays, round up to 8, plus the closing joist is 9.
- Screws: 22 x 9 x 2 = 396. Add 10% and buy 436.
Joist spacing moves the count more than deck size. Drop that 10 x 10 to 12" centers and it's 484; stretch to 24" and it's 264. Growing it to a 12 x 12 only adds 124.
Our size chart says "roughly 350 per 100 sq ft" and that's lower on purpose. It skips the closing joist and the rounded-up last board, which add about 45 screws on a 10 x 10.
How Many Screws Per Deck Board? Two, Not Three
Two screws per deck board at every joist it crosses, about 1" in from each edge. That's the rule on every deck we've laid in 28 years of timber work, and the baseline in the American Wood Council's deck construction guide.
One screw is a pivot. A deck builder who's inspected plenty of new decks saw one where the contractor drove a single screw per crossing, and the boards were cupping within two weeks. One screw can't hold a wet 2x6 flat while it dries.
A third screw adds nothing on a 5-1/2" board. The two edge screws already hold both sides down; a middle screw just adds a split or a hole for water. Save three per crossing for boards over 6" wide.
Composite is the same count but a different screw; see screws for Trex decking.
How Many Deck Screws for a 10x10, 12x16, 16x20 or 1,000 sq ft Deck?
A 10 x 10 needs 396 deck screws, a 12 x 16 needs 676, a 16 x 20 needs 1,120 and a 1,000 sq ft deck needs 3,348, all on 16" joists with 5-1/2" boards, before waste. The deck screw calculator table at the top has the buy figure and pack for each.
The per-square-foot rate falls as decks get bigger: near 4 on a 10 x 10, near 3.4 on 1,000 sq ft. The closing joist and the last partial board are a fixed cost that shows on a small deck and barely registers on a big one.
That's why the common "350 per 100 sq ft" rule is low for a small deck and about right for a large one. It gives 350 for a 10 x 10 that needs 396, and 3,500 for a 1,000 sq ft deck that needs 3,348. Most pages print 350 and stop; use the math under about 300 sq ft.
How Many Deck Screws Are in a 5 lb Box or a Pound?
About 435 deck screws at 2-1/2" and about 365 at 3" in a 5 lb box of Deck Mate; Grip-Rite runs about 475 and 350. Both sell by weight, so the box says "approximate" and the count moves with length, coating and batch.
| Screw length | Deck Mate per lb | Deck Mate 5 lb box | Grip-Rite per lb | Grip-Rite 5 lb box |
|---|---|---|---|---|
| 1-5/8" | about 147 | about 735 | about 200 | about 1,000 |
| 2" | about 126 | about 630 | about 140 | about 700 |
| 2-1/2" | about 87 | about 435 | about 95 | about 475 |
| 3" | about 73 | about 365 | about 70 | about 350 |
| 3-1/2" | about 56 | about 280 | about 55 | about 275 |
Those counts are the retailers' listings, and the listing doesn't always match the carton. One Deck Mate 3" box says 365 on the listing and 630 on the box.
So a 10 x 10 needing 436 is one 5 lb box of 2-1/2" Deck Mate, give or take a handful. That's the by-weight problem.
A by-count pack makes the table work. Eagle Claw's 304 stainless steel deck screws come in packs of 100, 350 and 1000, so 436 is a 350 plus a 100, and the #10 x 2-1/2" pack of 1000 covers anything up to a 12 x 16 at 15 cents a screw.
What Deck Screws Should You Buy?
The deck screws you should buy are Eagle Claw #10 stainless steel deck screws in by-count packs, the full count plus 10% in one order, so the build never stalls with boards loose. We frame with Simpson Strong-Tie structural fasteners. Try a sample pack first, or shop the full range.
How Many Extra Deck Screws Should You Buy?
Buy 10% more than the count: 40 extra on a 10 x 10, 112 on a 16 x 20. That covers snapped shanks, stripped heads, dropped screws, and the border and stair treads people forget to count.
What running out looks like, from builders who've done it:
- The mismatched finish. A deck builder reviewing a sloppy new deck read it straight away: the contractor ran out near the end and grabbed whatever was in the truck. It showed.
- The stalled build. A first-time builder ran out with the top pieces still loose, and the job sat until the next order arrived.
- The 200 wrong screws. A builder finishing blocking on a frame grabbed another box, drove about 200, then realized they were interior screws. Every one came back out.
Stainless steel deck screws are the ones you can't top up. No local store carries a matching #10 304 or 316 stainless steel deck screw, so a 40-screw shortfall is another delivery. Buy the full count plus 10% once.
Keep the spares. Boards twist as they dry, and a deck builder who used long screws on his whole deck still adds one every year where a board has moved. Snapped 3" heads take the rest if the clutch wasn't set on scrap first.
Things to Keep in Mind
- This count is deck boards only. Framing, joist hangers, ledger, railings and stairs are separate; see best structural screws for outdoor wood.
- Add the picture-frame border and stair treads to your board count before you order.
- A box sold by weight is an approximate count. Only a by-count pack matches the table.
