RightQty

Walls & interiors

Insulation calculator

Estimate whole batt or roll packages from net wall, ceiling, or attic area and the exact coverage printed on the selected product.

Product-label coverage

Calculate insulation packages

Measurement system
Exact product coverageCopy from the package label
A note only—RightQty does not select a required R-value.
Overage

Covers spillage, uneven depth, settling, and minor measurement differences.

Optional material costEnter your supplier's USD price

Material only; taxes, delivery, accessories, preparation, installation, and labor are excluded.

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Your material estimate

Insulation to order

5packages

Includes 10% overage and purchase-unit rounding where applicable.

Net surface area
160 sq ft
Waste-adjusted coverage
176 sq ft
Coverage per package
40 sq ft

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Shopping list

  • Insulation batt packages40 sq ft per package; user-selected R-13.5 packages
Calculation assumptions
  • The measured wall surfaces are rectangles; every counted surface uses the same dimensions.
  • Package coverage is copied from the exact product label and already reflects its batt or roll contents.
  • R-value is a user note only and never changes package coverage or selects a product.
  • This estimates material area, not required R-value, thermal design, installation suitability, or energy-code compliance.

Coverage math

How insulation packages are calculated

1

Net area

Multiply each equal rectangular surface, then subtract the combined openings.

2

Adjusted coverage

net area × (1 + waste ÷ 100).

3

Whole packages

Divide by the exact package coverage and round upward.

Worked example

A 20 × 8 ft wall using 40 sq ft packages

The wall has 160 square feet of net area. Ten percent overage raises coverage to 176 square feet. At 40 square feet per package, the estimate rounds up to 5 packages.

Product guidance

Coverage and R-value are separate inputs

  1. Measure the actual cavity surface. Treat different wall, ceiling, and attic rectangles separately.
  2. Copy package coverage. Batt count, width, length, and coverage vary by product.
  3. Use R-value only as a note. It does not change the entered package coverage.
  4. Do not reuse blown-in charts. Blown-in coverage changes with target R-value, thickness, weight, and manufacturer instructions and is outside this calculator.
No energy-code selection

RightQty does not choose a legally required R-value or determine thermal, fire, moisture, ventilation, vapor-control, or installation compliance.