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Underlayment Calculator

Figure out how much underlayment to buy for any floor — foam, cork, rosin paper, vapor barrier, plywood panels, or cement backer board — with rolls or sheets, fasteners, U.S. pricing, and a downloadable PDF material list.

Coverage varies by brand and thickness — always check the roll or sheet label. Match the underlayment to your finished floor and subfloor. For planning purposes only.

Area & Underlayment
1 Area to Cover
ft
×
ft
sq ft
sq ft
2 Underlayment Type
sq ft/roll
Check the label — roll coverage varies a lot by product
3 Materials & Cost
10%
~10% for most; bump to 15% for vapor barrier overlap or cut-heavy rooms
$/ sq ft
$/ box of 1,000
Fasteners auto-estimated at ~3 per sq ft (edges + field)
$/ box of 200
Screws auto-estimated at ~1.6 per sq ft (8" grid)
$/ 50 lb bag
~45 sq ft per bag with the recommended trowel
$/ 150 ft roll
$/ sq ft
Set 0 for DIY / materials only
Underlayment Estimate
Rolls To Buy
—
Enter your area to begin
Rolls (with waste) —
Sq Ft to Buy —
Coverage / Roll —
Full Cost Breakdown
Area to cover —
Underlayment —
TOTAL ESTIMATE—
Total cost / sq ft —
Sq Yards —
Install labor —
Cost Breakdown Chart
Estimated cost by category ($)
Overage Comparison — Your Area
OverageSq Ft to BuyRollsMaterial CostCost / sq ft

For your 300 sq ft area. More overage = fewer short pieces but a little more spend.