Price your attic at your own rate
The cost is plain multiplication, and the result shows every step. Attic floor area is length times width. The installed line is that area times your installed rate per square foot. Removal and air sealing are priced the same way, each with its own rate, and the other line is a dollar amount added as written. The total is the sum of the lines you entered.
Blank and zero do not mean the same thing. A blank field says the line is not part of this job, and the tool leaves it out. A zero says the line is part of the job but already paid inside another line. That way a quote that bundles everything into one lump sum is not read as a job with missing work.
Two worked examples. A 50 by 30 ft attic is 1,500 sq ft. At $1.80 per sq ft installed, $1.25 for removal and $0.75 for air sealing, the lines come to $2,700, $1,875 and $1,125. Add an other line of $250 and the total is $5,950. Those rates are entries chosen to show the arithmetic, not prices we found. Now take a 40 by 25 ft attic whose quote is a single figure of $2,400 for the whole job: enter 0 as the installed rate, $2,400 in the other line, and leave removal and air sealing blank. The total is $2,400, and the 0 tells anyone reading the result that the installation sits inside that figure.
Below your own lines, the tool applies the two published per-square-foot bands to the same floor area. Only two of the four publishers in the table print a per-square-foot band for the installation itself. TLS Energy Savers, an insulation contractor, prints $1.50–$3.00 per sq ft installed for standard fiberglass or cellulose on an attic floor. Homegenius Exteriors relays HomeAdvisor’s band of $1–$7 per sq ft. On the default 1,000 sq ft attic, that gives $1,500–$3,000 for the TLS band and $1,000–$7,000 for the HomeAdvisor band relayed by Homegenius. Both were read on October 21, 2026, and the result names each publisher next to its figures.
The two bands are never blended into one. They come from different sellers and cover different scopes, and one is far wider than the other; a midpoint between them would describe no quote anyone has written. Hold your own rate against each band separately. A rate inside both says little. A rate outside both is worth a question to the installer about what the line covers.
Foam sprayed on the roofline is worked out differently, from foam thickness, on the spray foam cost page.
Four publishers, four kinds of figure
| Publisher | Statement, as published | Page date |
|---|---|---|
| TLS Energy Savers ↗ | Attic insulation cost typically runs $1.50–$3.00 per square foot installed for standard fiberglass or cellulose attic-floor insulation. For a 1,000–1,500 sq ft attic, that usually puts a standard professional installation around $1,500–$4,500. | Not shown |
| TLS Energy Savers ↗ | That is why a standard removal-and-replacement project can move toward $2.50–$5.00 per square foot even when the attic floor area itself has not changed. | Not shown |
| Homegenius Exteriors, relaying HomeAdvisor’s band ↗ | Professionally installed attic insulation costs $1 to $7 per square foot, or $1,500 to $6,000 for most homes. | Not recorded |
| Thumbtack ↗ | The national average cost to insulate your attic ranges from $1,184 to $3,125, according to Thumbtack data, and most people pay around $1,923. | Last updated Jul 10, 2026 |
| Thumbtack, one installer’s quote ↗ | Cellulose blown-in insulation: $1.20-$1.25 per square foot from Juan Gutierrez of Capital Insulation in Tacoma, Washington. Price includes labor. | Last updated Jul 10, 2026 |
| QuoteIQ ↗ | Insulating an attic — about 1,000–1,500 sq ft of floor — costs roughly $1,500–$6,000 in 2026, depending on material and target R-value. | “in 2026” only |
| QuoteIQ ↗ | Old insulation is the wildcard: removing rodent-soiled or wet batts adds $1–$2 per sq ft, and air sealing penetrations first adds $0.50–$2.00. | “in 2026” only |
The table above holds seven statements from four publishers, each in its own words. They are not four measurements of the same thing, and the page keeps them apart for that reason.
TLS Energy Savers is an insulation contractor pricing the work it sells, and its page shows no publication date. It gives a per-square-foot band, a total of $1,500–$4,500 for a 1,000–1,500 sq ft attic, and $2.50–$5.00 per sq ft for a removal-and-replacement project. That last figure covers taking the old layer out and putting a new one in, so it is not a removal rate to stack on top of the installed rate.
Homegenius Exteriors is also a contractor, but its per-square-foot band is not its own: the $1–$7 figure links to HomeAdvisor. Its $1,500–$6,000 total is written “for most homes”, with no attic size attached. No page date was recorded when we read it.
Thumbtack is a platform that connects homeowners with installers. Its $1,184–$3,125 band comes from its own data, the method is not published, and the band is tied to no attic size. The page was last updated Jul 10, 2026. The same page quotes one firm, Capital Insulation in Tacoma, Washington, at $1.20–$1.25 per sq ft with labor included: a single installer’s price in one city, not a market figure.
QuoteIQ sells quoting software. It prints $1,500–$6,000 for about 1,000–1,500 sq ft of attic floor, dated only “in 2026”, with no method. It also lists two add-ons: $1–$2 per sq ft to remove wet or rodent-soiled batts, and $0.50–$2.00 per sq ft to air seal penetrations first.
Three kinds of number sit side by side here: rates per square foot, totals tied to an attic size, and totals tied to nothing. A rate can be multiplied by your floor area. A total for 1,000–1,500 sq ft can only be read against an attic in that span. A total with no area cannot be scaled at all. Averaging them would mix all three, so the page does not. The add-ons show what a total may or may not include, which is why the calculator gives removal and air sealing their own fields.
Check the installer’s receipt against 16 CFR 460.17
If you are an installer, you must give your customers a contract or receipt for the insulation you install. For all insulation except loose-fill and reflective insulation, the receipt must show the coverage area, thickness, and R-value of the insulation you installed. The receipt must be dated and signed by the installer.
If you put insulation in more than one part of the house, put the data for each part on the receipt. You can do this on one receipt, as long as you do not add up the coverage areas or R-values for different parts of the house. Do not multiply the R-value for one inch by the number of inches you installed.
For loose-fill, the receipt must show the coverage area, initial installed thickness, minimum settled thickness, R-value, and the number of bags used.
The rule quoted above puts the duty on the installer: whoever installs the insulation gives the customer a contract or receipt, dated and signed by the installer. For loose-fill the receipt has five items to show, and the form lists each one as its own check, in the order of the rule. Open the receipt next to the form and answer each line with Yes or No. A line left at “Not checked yet” is counted, never guessed: the result tells you how many items are still unchecked, so a half-read receipt never passes for a clean one.
A No is named in the result. Mark the last item of the loose-fill list as absent and the result reads “Missing from the receipt: number of bags used”; mark the level as absent and it reads “Missing from the receipt: R-value”. The date and the installer’s signature are checked the same way, as two formalities apart from the five items. The tool counts nothing itself. It reads what the installer wrote and tells you which of the listed items are not there.
For insulation other than loose-fill and reflective, the rule asks for three items instead: coverage area, thickness and the level. The checklist here follows the loose-fill list, the longer of the two. Two more sentences of the rule matter when the job covers more than the attic. One receipt may list several parts of the house, but each part keeps its own data: coverage areas and levels for different parts are never added together. And the level is never a one-inch figure multiplied by the inches installed. The number to type into the level field is the one written for the attic line.
Thickness gets two entries on a loose-fill receipt: the initial installed thickness and the minimum settled thickness. The calculator expects the first to be at least as large as the second. It subtracts one from the other and shows the difference as the settling allowance written on the receipt. Then it compares your own lowest depth reading with the minimum settled thickness.
Worked through: a receipt that says 18 in installed and 16 in settled carries a 2 in settling allowance. If your lowest reading is 16 1/2 in, the depth margin is 1/2 in, and the check passes. A second receipt says 12 in installed and 13 in settled. That order is backwards, and the result says the settled line exceeds the installed line. Measure 11 in at the lowest point and the depth falls 2 in short of the settled figure, a second warning. Enter the lowest reading, not the deepest, because the check is about the thinnest part of the floor. A reading exactly at the settled figure, 14 in against 14 in, passes with a margin of zero.
The last check reads the level. Type the number after R that the receipt claims, and the tool sets it against the ENERGY STAR level for your zone and attic, from the table in the next section. In zone 4A, with an attic that has no insulation today, the line is R60: a receipt claiming 60 meets it. In zone 3, with 3–4 inches already in place, the line is R38: a receipt claiming 30 falls short, and the result says the claimed level is below the recommendation. This compares two printed numbers. It does not test what is in the attic, and the section quoted above asks for the level to be written without naming one to reach.
Fill this part after the job, with the paper in hand. Before the job, the same five items make a list of what to ask the installer to put in writing.
The ENERGY STAR line for your zone
| Zone | If your attic is uninsulated | If you already have 3–4 inches of insulation |
|---|---|---|
| 1 | R30 | R25 |
| 2 | R49 | R38 |
| 3 | R49 | R38 |
| 4A and 4B | R60 | R49 |
| 6, 5, and 4C | R60 | R49 |
| 7 and 8 | R60 | R49 |
ENERGY STAR ↗: “Note: This guidance is based on the 2021 International Energy Conservation Code (IECC) Residential Provisions Chapter 4 Table R402.1.3. See Code for more detailed guidance.”
The table above is ENERGY STAR’s guide for adding insulation to existing wood-framed buildings. Its own note ties it to the 2021 IECC, Table R402.1.3, and sends readers to the code for detail. It is a recommendation, not a code minimum, and the calculator labels it that way each time it shows it.
Two of its columns concern the attic, and the form’s second menu uses their headings word for word: “If your attic is uninsulated” and “If you already have 3–4 inches of insulation”. Pick the one that matches the attic as it is before the work. The answer changes the line in every row: in zone 2, R49 for an empty attic and R38 with the existing layer; in zones 4A and 4B, R60 and R49. Zone 1 is the lowest row, at R30 and R25. An attic that fits neither heading has no column of its own in this table, and the page does not invent one.
Read the zone column with care. The fifth row is printed “6, 5, and 4C”, highest zone first, and 4C sits there rather than beside 4A and 4B. The selector finds your zone inside whichever label holds it, so zone 5 and zone 4C land on the same row. Zones 7 and 8 share the last row.
On this page the level has one job: it is the yardstick for the number after R on the installer’s receipt. The calculator does not turn it into inches or into a quantity of material, and it does not say what an attic below the line should buy. If the quote names a target level, compare it with the row before the work. When the receipt arrives, compare again. Quote and receipt should name the same level; if they do not, ask the installer why.
Leave the vents open: R806.2 and R806.3
The minimum net free ventilating area shall be 1/150 of the area of the vented space.
Exception: The minimum net free ventilation area shall be 1/300 of the vented space provided both of the following conditions are met:
- In Climate Zones 6, 7 and 8, a Class I or II vapor retarder is installed on the warm-in-winter side of the ceiling.
- Not less than 40 percent and not more than 50 percent of the required ventilating area is provided by ventilators located in the upper portion of the attic or rafter space. Upper ventilators shall be located not more than 3 feet (914 mm) below the ridge or highest point of the space, measured vertically. The balance of the required ventilation provided shall be located in the bottom one-third of the attic space. Where the location of wall or roof framing members conflicts with the installation of upper ventilators, installation more than 3 feet (914 mm) below the ridge or highest point of the space shall be permitted.
Where eave or cornice vents are installed, blocking, bridging and insulation shall not block the free flow of air. Not less than a 1-inch (25 mm) space shall be provided between the insulation and the roof sheathing and at the location of the vent.
R806.2, quoted above from Colorado’s adoption of the IRC 2021, sets a minimum net free ventilating area of 1/150 of the area of the vented space. The calculator takes the attic floor you entered as that area, divides it by 150, and converts the result to square inches by multiplying by 144, the square inches in a square foot. On the default 1,000 sq ft attic, that is 6.67 sq ft, or 960 sq in of open vent area.
The exception halves it to 1/300, and only when both conditions hold. The first only bites in climate zones 6, 7 and 8: a Class I or II vapor retarder on the warm-in-winter side of the ceiling. The second applies in every zone: not less than 40 and not more than 50 percent of the required area sits in upper vents no more than 3 ft below the ridge or highest point, measured vertically, with the balance in the bottom one-third of the attic space. The form asks both as yes-or-no questions, and “No or not known” keeps the 1/150 ratio.
With both met on the 1,000 sq ft attic, the minimum drops to 3.33 sq ft, or 480 sq in. The tool then splits it: 192–240 sq in in the upper vents, which is 40 to 50 percent of 480, and 240–288 sq in low in the attic for the balance. On a 50 by 30 ft attic in zone 7, with a vapor retarder and the upper split, the minimum is 720 sq in, with 288–360 sq in up high and 360–432 sq in down low.
The conditions do not trade against each other. In zone 6 with the upper split but no vapor retarder, the exception fails, the ratio stays at 1/150, and the result explains why. In zone 7 with a vapor retarder but no upper split, the ratio also stays at 1/150, and no warning appears, because no split was claimed. The quoted text also permits upper vents lower than 3 ft below the ridge where framing members are in the way; the yes-or-no question leaves that call to you and the full text.
The low vents are where a new floor layer meets the roof. R806.3, quoted above as IRC 2024 from the Texas Windstorm Insurance Association’s adoption, says blocking, bridging and insulation must not block the free flow of air where eave or cornice vents are installed, and asks for not less than a 1-inch space between the insulation and the roof sheathing at the vent. Keeping that space open is part of the work. If your quote prices it separately, under baffles or any other name, put it in the other line so the total carries it.
The result is an area, not a shopping list. It gives no vent count and names no product, because a count depends on the vents chosen, and that choice belongs to the job. Each edition is read here through a single adoption, and adoptions and amendments vary, so confirm the rule in force where you live before relying on the figure.
The federal tax credit for this work
The credit in question is the Energy Efficient Home Improvement Credit. Its IRS page lists December 31, 2025 as the end of the credit. The same page words that end two ways, “through December 31, 2025” in one sentence and “before December 31, 2025” in another, so this page makes no statement about work finished on that day. The calculator computes no credit and no cost net of one, and it names no other incentive. For anything that touches a tax return, read the IRS page itself.
What owners reported for insulation projects
| Area | Owner reports | Lower quartile | Median | Upper quartile |
|---|---|---|---|---|
| United States | 888 | $500 | $1,500 | $2,900 |
| Northeast | 177 | $500 | $1,500 | $2,900 |
| Midwest | 189 | $360 | $1,000 | $2,500 |
| South | 294 | $510 | $1,500 | $3,000 |
| West | 228 | $500 | $1,700 | $3,000 |
The table above comes from the U.S. Census Bureau’s American Housing Survey 2023, job type 20, “Insulation”. It holds every insulation project owner-occupants reported: attic, walls or floors, any material, hired out or done themselves. The costs are what owners said they spent, rounded and topcoded on the public file. Nationally, 888 reports give a lower quartile of $500, a median of $1,500 and an upper quartile of $2,900.
Weighted, 44.66 % of these projects were do-it-yourself jobs, whose reported cost can leave labor out. Across the four regions, the median runs from $1,000 in the Midwest to $1,700 in the West, with the Northeast and the South at $1,500.
None of this is an attic price, and none of it is a rate per square foot: the job type does not separate the attic from walls and floors, and its figures carry no area to divide by. For that reason the calculator never places your total among these quartiles. A median that pools wall, floor and attic jobs, hired and do-it-yourself, says nothing about whether your quote is high. Read it as a picture of what owners spent on insulation, then price your own attic from its floor area.
Attic insulation cost questions
How much does it cost to insulate a 1500 sq ft attic?
It depends on the rate in your quote: 1,500 sq ft times that rate, plus any removal or air sealing lines. Applied to 1,500 sq ft, the TLS Energy Savers band of $1.50–$3.00 per sq ft gives $2,250–$4,500, and HomeAdvisor’s $1–$7 band, relayed by Homegenius, gives $1,500–$10,500. For a 1,000–1,500 sq ft attic, TLS prints a total of $1,500–$4,500 and QuoteIQ $1,500–$6,000.
What is the cheapest way to insulate my attic?
The records behind this page rank no material or method by price, so this page does not either. What it can do is put competing quotes on the same footing: enter each one’s rates per square foot for the same floor area and compare them line by line. The lowest per-square-foot figure in the table, $1.20–$1.25 with labor, is one Tacoma, Washington installer’s quote relayed by Thumbtack, not a national figure.
How much does it cost to insulate a 2000 square foot attic?
Multiply 2,000 sq ft by your quote’s rate. For scale, the TLS Energy Savers band gives $3,000–$6,000 on that area, and HomeAdvisor’s band relayed by Homegenius gives $2,000–$14,000. At an entered rate of $2.00 per sq ft, the installed line is $4,000. The same attic needs 13.33 sq ft, or 1,920 sq in, of net free vent area at 1/150.
Is insulating your attic worth it?
This page gives no savings figure: none was read on an ENERGY STAR page on October 21, 2026. What it gives instead is the ENERGY STAR level for your zone and attic, a way to check whether the installer’s receipt claims it, and the vent area the work must leave open. On money, the IRS page lists December 31, 2025 as the end of the federal credit, and the calculator computes no credit.
How much does it cost to insulate a 700 sq ft attic?
A 700 sq ft house and a 700 sq ft attic are not the same thing, so measure the attic floor itself. If the attic floor is 700 sq ft, for instance 28 by 25 ft, the TLS Energy Savers band gives $1,050–$2,100 and HomeAdvisor’s band relayed by Homegenius gives $700–$4,900. Your own quote’s rate decides the real figure. The vent area at 1/150 is 672 sq in.
What does 1,000 sq ft of attic insulation cost?
At 1,000 sq ft, the default 40 by 25 ft attic in the calculator, the TLS Energy Savers band gives $1,500–$3,000 and HomeAdvisor’s band relayed by Homegenius gives $1,000–$7,000. Thumbtack’s own band of $1,184–$3,125 is tied to no attic size, so it cannot be scaled to yours. The vent area for that floor is 960 sq in at 1/150. Enter your quote’s rates to set your own lines beside these bands.
How does this attic insulation cost calculator work?
It runs five steps in order. Length times width gives the attic floor. That area sets the net free vent area at 1/150, or at 1/300 when you confirm both R806.2 conditions. Your climate zone and the attic as it is pick the ENERGY STAR level. The receipt section marks each listed item present or missing and compares the thicknesses. Last, your rates make the cost lines. Only the example measurements are prefilled. The method is on how we calculate.
How much does attic insulation cost per square foot?
Three publishers state an installed rate per square foot, each in its own terms. TLS Energy Savers prints $1.50–$3.00 installed for standard fiberglass or cellulose on an attic floor. Homegenius relays HomeAdvisor’s $1–$7. Thumbtack quotes one Tacoma installer at $1.20–$1.25, labor included. For extra lines, TLS prints $2.50–$5.00 for a removal-and-replacement project, and QuoteIQ $1–$2 for removal and $0.50–$2.00 for air sealing. The page never averages them.
What does DIY attic insulation cost?
No do-it-yourself price appears in the records behind this page. The American Housing Survey’s insulation job type mixes hired and do-it-yourself projects, 44.66 % of them do-it-yourself when weighted, so its $1,500 median is not a do-it-yourself price. The receipt rule binds installers; the vent rule applies to whoever does the work. The calculator still multiplies any rate you enter.
Is this attic insulation cost calculator free?
Yes. It is free and needs no account. The calculation runs on the page itself, so you can change any field, from the attic size to a single receipt item, and read the result again as often as you need.
How do I measure attic square feet for insulation?
Measure the length and width of the attic floor in feet and multiply them: 40 ft by 25 ft is 1,000 sq ft. For an attic that is not a rectangle, split it into rectangles, add their areas, and enter a length and width whose product is the total. Measure the floor you are insulating, not the house footprint or the roof. The same area drives the vent ratio, so a wrong area skews both the cost and the vent figure.
Read the result with its boundaries
- Attic floor insulation in an existing home. No quantity of material is computed: the receipt check reads what the installer wrote.
- The vent area uses the attic floor you enter as the area of the vented space, under R806.2 as read in Colorado’s adoption of the 2021 IRC. Confirm the rule adopted where you live.
- ENERGY STAR levels are retrofit recommendations, not a code minimum.
- No tax credit is computed. The IRS page lists December 31, 2025 as the end of the credit.
- Every rate and every line is a figure you enter. Published figures are shown with their publisher and date, never as an average. Spray foam is priced on the spray foam insulation cost calculator.