Subfloor Calculator
Estimate plywood sheets, square feet, and cost
Length of the room
Width of the room
Standard plywood panel size
Square Feet
—
sq ft
Plywood Sheets
—
sheets
Estimated Cost
—
USD
Disclaimer: Results are estimates based on standard formulas. Not a substitute for professional advice from a licensed contractor, engineer, or architect. Verify all calculations before making purchasing or construction decisions.
How to Use This Calculator
Installing a subfloor? Accurate plywood estimates prevent material shortages and reduce waste. Our calculator sizes sheets for standard 4x8 panels with a 10% waste allowance.
- Measure the length and width of your room in feet
- Confirm your plywood sheet size (4x8 ft is standard)
- Enter your dimensions in the calculator
- Stagger panel seams and glue edges for a squeak-free floor
Expert Insights
Smart analysis for your Flooring project
Panel Layout Optimization
Staggering plywood seams by half a panel strengthens the floor and reduces squeaks. AI factors 10% waste for cuts around walls and openings.
Fastener & Adhesive Strategy
Subfloor adhesive plus ring-shank screws every 6 in at edges and 12 in in the field prevents nail pops and floor movement.
Thickness Selection
3/4 in T&G plywood for 16 in joist spacing. For 24 in spacing, use 7/8 in or engineered panels. AI matches thickness to your joist layout.
Calculation Formula
Room area = Room length x Room width
Sheets = ceil(Room area / 32 x 1.1)
Estimated cost = Sheets x $35
Subfloor Material Comparison
| Material Type | Thickness | Cost per Sheet | Best For | Waste Factor |
|---|---|---|---|---|
| CDX Plywood | 5/8 or 3/4 in | $35-$50 | Moisture resistance | 10% |
| T&G Plywood | 3/4 in | $40-$55 | Standard subfloor | 10% |
| OSB Panel | 3/4 in | $25-$40 | Budget builds | 10% |
| Engineered Subfloor | 3/4-7/8 in | $45-$65 | Long spans | 10% |
Authority References
Our calculations are based on guidelines and standards from these authoritative sources:
- American Plywood Association (APA) — Engineered Wood Construction Guide. Learn more
- International Residential Code (IRC) — Chapter 5 — Floors. Learn more
- American Wood Council (AWC) — Wood Frame Construction Manual. Learn more
Frequently Asked Questions
What thickness plywood is used for subfloor?
Standard subfloor plywood is 5/8 inch or 3/4 inch thick T&G (tongue and groove) panels. Most residential construction uses 3/4 inch for joists spaced 16 inches on center.
How many square feet does a 4x8 sheet of plywood cover?
A standard 4x8 foot sheet of plywood covers 32 square feet. Always add 10% for waste due to cuts around walls and openings.
How much does subfloor plywood cost?
Subfloor-grade plywood (3/4 in T&G) averages $35-$50 per 4x8 sheet. OSB subfloor panels run slightly less at $25-$40 per sheet.