Attic insulation cost calculator
Measure the attic, drop in the $/ft² from your own quote and see the job total with a contingency buffer — a planning number to sanity-check a bid, not a bid itself.
Calculator
A 1,200 ft² attic at $1.75/ft² is about $2,310.00 with 10% contingency. Blown-in attic insulation typically runs $1.00–2.80/ft² installed (labeled) — enter your quote.
Formula
total = attic_area_ft² × your_$/ft² × (1 + contingency%)
The $/ft² is the price you enter from a real quote (material + labor). Nothing here is hardcoded — blown-in, batt and foam all price differently, so the tool never guesses your rate. The contingency covers tight access, old wiring to work around, top-plate air-sealing and the odd extra bag.
Worked example
A 1,200 ft² attic quoted at $1.75/ft² installed, with a 10% contingency:
1,200 × $1.75 = $2,100, then $2,100 × 1.10 = $2,310.
That $2,310 is your planning total. If a contractor’s bid lands well under $2,100 ask what R-value and how many inches they are actually installing; if it lands well over, ask what the extra covers — removal of old insulation, baffles, a walkway, or heavy air-sealing.
What to measure & where the money hides
Measure the footprint, not the roof. Blown-in and batt cost track the attic floor area, so use length × width of the insulated ceiling below, not the sloped roof area. For an irregular attic, break it into rectangles and add them up.
What the $/ft² already includes matters. A blown-in attic runs roughly $1.00–2.80/ft² installed (labeled band); closed-cell spray foam is far higher, $1.50–4.50/ft². If your quote is a flat $/ft², confirm it is for the R-value you actually want — going from R-30 to R-49 is more material and a higher rate.
Common gotchas that move the price. Removing old, wet or rodent-fouled insulation is a separate line item (see the removal & replacement tool). Add-ons that are easy to forget: attic-hatch weatherstripping, insulation baffles at the eaves, a raised platform over a furnace or storage, and dam boxes around recessed lights and the flue. Each is small, but together they eat the contingency fast.
What this is not. It is a planning estimate, not a bid, and not an energy audit. It sizes the spend; it does not tell you the attic is air-sealed or ventilated correctly — that is a job for the installer and your local code.
Reference table
Labeled installed price bands (material + labor) as a sanity guide — you enter your own quote price.
| Attic material | Typical installed $/ft² |
|---|---|
| Blown-in (loose fill) | $1.00–$2.80 |
| Fiberglass batt | $0.80–$2.40 |
| Cellulose | $1.00–$2.60 |
| Open-cell spray foam | $1.00–$2.50 |
| Closed-cell spray foam | $1.50–$4.50 |
Labeled planning bands, not live prices — confirm with itemized quotes from licensed, insured contractors.