Inputs
White theme • Pro featuresSwitching units auto-converts fields below.
Covers trimming, seams, and offcuts.
Optional. Used for cost estimates.
Coverage computed from dimensions
ft
ft
ft²
Auto = width × length
Rooms / Areas
| # | Length | Width | Area | Notes | |
|---|---|---|---|---|---|
| 1 |
ft
|
ft
|
ft²
|
Results
Total net area120.00 ft²
Waste / overlap9.00 ft²
Adjusted area129.00 ft²
Coverage per unit48.75 ft²
Units required3
Estimated cost$0.00
Leftover / shortfall17.25 ft² leftover
Example products
| Type | Spec | Coverage / unit |
|---|---|---|
| Roll | 15 in × 39 ft | 48.75 ft² |
| Roll | 23 in × 39 ft | 74.75 ft² |
| Batts | 15 in × 96 in, 10/bag | 100.00 ft² |
| Batts | 23 in × 93 in, 8/bag | 118.67 ft² |
Formula used
- Area per room =
length × width(rectangular approximation). - Total net area = sum of room areas.
- Waste / overlap =
Total net area × (waste% ÷ 100). - Adjusted area =
Total net area + Waste area. - Coverage per roll =
roll width × roll length. - Coverage per bag =
batt width × batt length × batts per bag. - Units required =
ceil(Adjusted area ÷ Coverage per unit). - Leftover =
Units × Coverage − Adjusted area(negative indicates shortfall). - Estimated cost =
Units × Unit cost.
All calculations occur in the selected unit system. Switching systems converts inputs and outputs consistently.
How to use
- Select your unit system and enter a reasonable waste percentage.
- Choose the product type and enter the dimensions or bag details.
- Add rooms. Edit length and width to match each area.
- Optionally set a per-unit cost for budget estimation.
- Press Calculate. Review units required, cost, and leftover.
- Export results to CSV or PDF for records or procurement.
FAQs
For complex shapes, break the space into rectangles or add extra waste. This tool assumes rectangular regions for speed and simplicity.
Counts are driven by area coverage. Thickness/R‑value affects product selection, not the simple area-based coverage calculation.
Use one run per product type to see units required. Export each set and combine in your purchase list.
Typical projects assume 5–12% depending on irregularities, framing layout, and installer experience. Increase for angled walls or obstacles.
All inputs convert between feet and meters using 1 ft = 0.3048 m. Areas convert by squaring that factor.
Yes. After adding a row, type your known area in the Area field. Length/width will be ignored for totals.