Plywood Subfloor Calculator
Sheets, screws, and adhesive for a plywood or OSB subfloor.
10% for rectangles, 15% for rooms with angles and jogs.
You need
14 sheets
Waste included. Stagger end joints and leave a 1/8 in gap at panel ends.
- Subfloor screws
- 490 screws
- Adhesive (28 oz tubes)
- 5 tubes
- Floor area
- 384 sq ft
Estimates only. Verify quantities before ordering.
How this is calculated
Sheets = area x (1 + waste) / 32 sq ft per 4x8 sheet, rounded up. Screws assume about 35 per sheet (6 in edges, 12 in field on 16 in joists). Adhesive assumes one 28 oz tube per 3 sheets.
Enter the floor dimensions and this calculator counts the 4 x 8 sheets (32 square feet each) of plywood or OSB, plus the screws and construction adhesive that make a subfloor solid and squeak-free. The math is the same for tongue-and-groove subfloor panels, sheathing, and underlayment; only the thickness and grade change.
Sheets should run perpendicular to the joists with end joints staggered between rows, which is where the waste factor goes: end cuts, notches around corners, and the partial sheets that finish each row. 10% covers a rectangular room; add more for rooms with jogs, angles, or many penetrations.
Sheets for common floor sizes
Rows assume 4 x 8 sheets with 10% waste, screws at 35 per sheet, and one adhesive tube per 3 sheets.
| Floor size | Sheets | Screws |
|---|---|---|
| 12 x 12 ft room | 5 sheets | 175 screws |
| 16 x 12 ft room | 7 sheets | 245 screws |
| 24 x 16 ft addition | 14 sheets | 490 screws |
| 24 x 24 ft garage loft | 20 sheets | 700 screws |
| 40 x 28 ft full story | 39 sheets | 1,365 screws |
Common questions
What thickness of subfloor plywood do I need?
With joists at 16 inches on center, 3/4 inch tongue-and-groove plywood or OSB is the standard for a floor that will carry tile or hardwood; 23/32 OSB subfloor panels are the common commodity version. Wider joist spacing or stone tile calls for thicker panels or an added underlayment layer.
Should I glue the subfloor down?
Yes. A bead of construction adhesive on every joist plus screws is the glued-and-screwed standard that prevents squeaks, stiffens the floor, and is required by many flooring warranties. One 28 oz tube covers roughly 3 sheets' worth of joist lines.
Screws or nails for subfloor?
Screws hold far better against the wood movement that causes squeaks. Use subfloor-rated screws about 6 inches apart on panel edges and 12 inches in the field, roughly 35 per sheet on 16 inch joists. Ring-shank nails are acceptable with adhesive, but smooth nails work loose.
Which way do subfloor sheets run?
Long dimension perpendicular to the joists, with the tongue-and-groove edges meeting between joists and end joints landing on a joist, staggered half a sheet between rows. Leave a 1/8 inch gap at panel ends per APA guidance; panels swell slightly with humidity.