Insulation cost per square foot calculator
Multiply your area by your own $/ft² and get the material or installed total in one line — then sanity-check it against labeled per-foot bands.
Calculator
At $1.50/ft², 1,000 ft² is about $1,500.00. Installed insulation runs roughly $0.80–2.40/ft² (fiberglass batt) to $1.50–4.50/ft² (closed-cell foam) — labeled bands, not a quote.
Per-square-foot is the fastest way to size an insulation budget: pin down the area and a realistic $/ft² and the total falls out. The catch is that “$/ft²” hides a lot — it changes with the material, the R-value, whether labor is in the number, and how hard the space is to reach. Enter the figure from your own quote (or work it out from a bag/board price divided by its coverage) and use the bands below only to check you are in the right ballpark.
Formula
total = area_sqft × price_per_sqft
Measure the real surface area, not the floor plan: a 1,000 ft² attic footprint with a steep roof, or a wall run once you subtract windows and doors, is not the same number. For the installed cost, use an installed $/ft² (material + labor); for a materials-only figure, use the bag/board price divided by its labeled coverage.
Worked example
A 1,000 ft² attic at your quoted $1.50/ft²:
1,000 × $1.50 = $1,500
That lands mid-band for blown-in attic insulation ($1.00–2.80/ft² installed). Swap in $0.90/ft² and it is $900; at $2.50/ft² for closed-cell it is $2,500 — same area, very different job.
What the per-foot number hides (and how to measure it)
Before you trust a $/ft², know what is inside it:
- Material vs installed. A retail bag price is materials only. A contractor’s $/ft² usually includes labor, setup and cleanup — two to three times the material number is normal for a small job.
- R-value drives it. R-49 needs far more material per foot than R-19, so “$/ft²” without an R attached is nearly meaningless. Use the by-R tool if you know your target.
- Access and prep. A low attic, a crawlspace you belly-crawl, removal of old wet insulation, or heavy air-sealing all push the real per-foot number up — they rarely show in a headline rate.
- Measure net area. Subtract openings on walls; for a sloped roof or cathedral, use the actual sloped area, not the footprint. Getting the area wrong is the biggest source of a blown budget.
The bands here are labeled planning ranges, not a price list. They move with region, material and labor and they age — that is exactly why this tool holds no price and asks for yours. Always confirm with itemized written quotes from licensed, insured insulation contractors.
Reference table
| Material | Typical installed $/ft² |
|---|---|
| Fiberglass batt | $0.80–$2.40 |
| Blown-in (fiberglass / cellulose) | $1.00–$2.80 |
| Cellulose (dense-pack) | $1.00–$2.60 |
| Mineral wool (Rockwool) | $1.40–$4.00 |
| Open-cell spray foam | $1.00–$2.50 |
| Closed-cell spray foam | $1.50–$4.50 |
| Rigid foam board | $1.50–$3.50 |
| Radiant barrier | $0.30–$0.80 |
Labeled planning bands (installed = material + labor), not a live price list — a sanity guide only. You enter the real price from your own quotes.
Frequently asked questions
How much does insulation cost per square foot?
It depends on the material and whether labor is included. As labeled installed planning bands: fiberglass batt roughly $0.80–2.40/ft², blown-in about $1.00–2.80/ft², and closed-cell spray foam $1.50–4.50/ft². Enter your own quoted figure — these are only a sanity guide.
Does this include labor?
Only if the $/ft² you enter does. Use an installed rate (material + labor) for the job total, or a bag/board price divided by its coverage for a materials-only figure. Do not mix the two.
How do I turn a bag price into a $/ft²?
Divide the bag or board price by the coverage printed on it. A bag that covers 37 ft² at your target R for $34 is about $0.92/ft² in material — before labor.
What area do I use for a sloped attic or cathedral?
Use the actual surface area of the sloped plane, not the floor footprint — a steep roof can be 15–30% more area than the floor below it.
Why does the same square footage cost so differently?
R-value, material, access, prep and whether old insulation has to come out all move the per-foot rate. That is why one $/ft² number is a starting point, not a bid.