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Blown-In Insulation Bag Count Calculator

Calculate how many bags of blown-in insulation are needed for an attic or wall cavity at a target depth.

  • Answers as you type
  • Every formula cited
  • Calculated in your browser
SettingsSettings for this calculationUS
Market
Imperial · sales tax
The attic or cavity area to be covered with blown-in insulation.

Measure the floor area (for attics) or the wall/cavity face area being filled.

The target settled/installed depth of loose-fill insulation.

Set this to the depth that achieves your target R-value per the manufacturer's coverage chart for the product being installed.

The volume of coverage one bag provides at the target installed depth, per the manufacturer's chart.

Coverage yield per bag decreases as target depth (and density) increases — always read the yield figure for your specific target depth, not a generic average.

Bags needed

12 bags

Medium confidence

Bag yield depends on the target installed density, which varies by depth and product per the manufacturer's coverage chart — always use the yield figure printed on the bag for your specific target depth/R-value, not a generic assumption.

Total insulation volume
39.17 yd³
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Bags needed = ceil(required volume ÷ the bag's rated coverage yield at the installed density), the standard method for estimating blown-in (loose-fill) insulation material from the manufacturer's bag coverage chart

Inputs used

Area to Insulate
1080 sq ft
Target Installed Depth
11.75 in
Bag Coverage Yield at This Depth (m³ per bag)
2.6

Intermediate steps

Total insulation volume
39.17 yd³
Final result12 bags

Confidence note: Bag yield depends on the target installed density, which varies by depth and product per the manufacturer's coverage chart — always use the yield figure printed on the bag for your specific target depth/R-value, not a generic assumption.

What this calculation does not cover

  • Depth on a ruler is not R-value, and the bag count is what proves it. A coverage chart ties each R-value to a minimum number of bags per unit of area as well as to a depth, so a yield taken from a lower-density line gives fewer bags at the same finished depth — the attic measures right, performs below its rating, and nothing on site catches it afterwards.
  • Attic yields do not transfer to closed cavities. Dense-packing a wall or a cathedral cavity is done at a far higher density to stop the material settling and leaving a void at the top, which cuts the coverage a bag gives by half or more, and the fill goes in through a tube around fire blocking, wiring and bracing rather than being blown across an open floor.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

blown insulation 11.75 inblown insulation 29.85 cmceiling

Part of bigger jobs

This trade is one line of a job takeoff. Run the whole job and every other trade comes back with it, off the same measurements.

Or plan the space itself: measure it once, doors and windows included, and this figure comes back worked out on that space, with what goes with it.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1

Regulatory standards & verification citations1
  1. Bags needed = ceil(required volume ÷ the bag's rated coverage yield at the installed density), the standard method for estimating blown-in (loose-fill) insulation material from the manufacturer's bag coverage chart
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Protection this work requires

  • Stop and check first. Textured ceiling coatings, board behind panels, floor tiles and bitumen adhesive in older buildings — built before asbestos was banned or phased out where you are — can contain asbestos, and drilling or sanding them releases fibres. Do not disturb it — have it sampled first. This is not a job for better PPE.

Tools and safety for this job

To blow loose-fill insulation. Generic types, no brands, no prices.

  • Mineral and glass wool irritate skin, eyes and airways: cover your arms, wear a P2/N95 respirator while cutting, and rinse in cold water — hot water drives fibres in.
  • Most fatal falls on small jobs are from under three metres: use a tower or a ladder tied at the top, and never work off the top two rungs.
Show the 5 tools this job needs

Essential

  • Crawl boards

  • Insulation blower and hose

  • Tape measure

Recommended

  • Extension ladder

Optional

  • Dust extractor or vacuum with a fine filter

Also needed as materials: bagged loose-fill.

what each insulation tool is for, and the spec that decides which to buy where one does.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Still deciding? Batt vs Blown-In Insulation · Radiant Barrier vs Blown-In Insulation — the factors that actually differ, with no invented prices.

Already have some? How much attic will my bags of blown-in insulation cover?

The data behind it: Production rates by operation

How to calculate blown-in insulation bag count in 4 steps

  1. Area to InsulateThe attic or cavity area to be covered with blown-in insulation.
  2. Target Installed DepthThe target settled/installed depth of loose-fill insulation.
  3. Bag Coverage Yield at This Depth (m³ per bag)The volume of coverage one bag provides at the target installed depth, per the manufacturer's chart.
  4. Bags neededThe tool computes the bags needed from those figures and shows the formula, its sources, and a confidence rating alongside it.

Bags needed by area to insulate

Page defaults, not your figures above.

Area to InsulateBags needed (bags)
500 sq ft6
1,000 sq ft11
1,500 sq ft17
2,000 sq ft22

Frequently asked questions

Why does bag coverage yield change with depth?
Because a bag contains a fixed mass of material, and installing it at a greater depth spreads that mass over less floor area. The coverage yield per bag drops as the target depth increases, which is why manufacturers publish coverage charts: a greater depth (higher density, for higher R-value per inch) compresses the same mass into less floor area.
Should I round up the number of bags?
Yes — bags are a whole-unit product, so the required volume is divided by the per-bag yield and rounded up to ensure full coverage at the target depth across the whole area.
Does settling reduce the depth over time?
Yes, somewhat, which is why manufacturers' coverage charts already build in an initial installed depth that allows for expected settling and still reaches the rated long-term R-value. Always install to the chart's stated initial depth, not just the nominal settled depth.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.