Screw length — | about — lb (~—) | ~—/lb
Shopping Summary
- Screws required—
- Waste—
- Purchase quantity—
- Recommended box—
- Approx weight—
- Estimated cost—
Common Screw Coverage
| Project | Typical screws |
|---|---|
| Decking | 350 – 450 per 100 sq ft |
| Drywall | 30 – 40 per sheet |
| Subfloor | 50 – 75 per sheet |
| Framing (structural) | Varies by connection |
| Cabinetry | 6 – 10 per cabinet |
Screw Length Guide
| Material | Length |
|---|---|
| Deck boards | 2-1/2 in |
| Drywall 1/2 in | 1-1/4 in |
| Drywall 5/8 in | 1-5/8 in |
| Subfloor | 2 – 2-1/2 in |
| Cabinets / furniture | 1-1/4 – 2-1/2 in |
| Framing | 3 – 3-1/2 in |
Rule of thumb: the screw should go at least twice the thickness of the top material into the base.
How Many Screws Do I Need?
Screw quantity comes from how much material you are fastening and how densely, then you add a waste factor and convert to the box you actually buy. A deck uses about 350 to 450 screws per 100 square feet, drywall about 30 to 40 per sheet, and framing varies by connection. This calculator turns your project, screw type, and area or count into a required number, a waste-adjusted purchase quantity, the box count to buy, an approximate weight, and a cost, so you shop in boxes instead of guessing at a wall of nearly identical cartons.
Buying Screws by the Box
Screws are sold by count or by weight, and the right unit depends on the job. Deck and drywall screws come in count boxes of 1,000, 2,500, and 5,000, while specialty and structural screws often come in small boxes or by the pound. Knowing the screws per pound, roughly 75 per pound for 2-1/2 inch deck screws up to a few hundred for short drywall screws, lets you convert a count into pounds and pick between a count box and a weight box.
Screw Length and Type
Match the screw to the material and the thickness. The common rule is that the screw should penetrate the base material by at least twice the thickness of the piece being fastened, so a 3/4 inch deck board wants a 2 to 2-1/2 inch screw. Use coated or stainless deck screws outdoors, coarse-thread drywall screws into wood and fine-thread into metal, structural screws where a lag once went, and cabinet screws with a broad washer head for hanging. The right type matters as much as the count.
Frequently Asked Questions
How many screws do I need? Multiply your area or count by the per-unit rate, then add about 10 percent waste.
What box size should I buy? Match the box to the total: a 2,500 count box covers a typical deck, smaller boxes for small jobs.
What screw length should I use? Enough to penetrate the base by about twice the top material thickness; 2-1/2 inch is the deck default.
How many deck screws per square foot? Roughly 3.5 to 4.5, or 350 to 450 per 100 square feet.