Why this exists
Searching for how much insulation you need turns up two kinds of results. Retailer calculators that ask for square footage and return a bag count with no explanation. And contractor sites that want your phone number before telling you anything.
Neither answers the actual question, which is not "how many bags" but "what does my specific attic need, why that number, and is it worth doing".
How we approach it
Results first, always
No email, no phone number, no lead form in front of your answer. If we cannot be useful before asking for something, we have not earned it.
Try the calculatorThe math is visible
Every result has a breakdown showing area, R-value delta, coverage, waste, and rounding. A number you cannot check is one you have to take on faith.
See our methodologyWe tell you when to stop
If your existing insulation already meets the recommendation, the calculator says so and suggests air sealing instead of selling you more material.
Why more is not betterNo invented numbers
No live prices we do not have, no energy-savings estimates we cannot substantiate, no reviews or contractor listings we made up.
Our affiliate positionHow this is funded
The intent is to earn revenue through retailer affiliate links on shopping lists, and eventually through contractor referrals.
Affiliate links are active with Amazon. We may earn a commission when you buy after following one of those links, at no extra cost to you. As an Amazon Associate I earn from qualifying purchases. There are no contractor partnerships. Every page carrying a monetised link says so; see our affiliate disclosure.
Amazon
Affiliate partner
We are a participant in the Amazon Services LLC Associates Program. If you buy after following one of our Amazon links we may earn a small commission, at no extra cost to you.
Home Depot
Plain link
Ordinary links to Home Depot. They earn us nothing today. If that ever changes it will say so here and on every page carrying one.
Lowe's
Plain link
Ordinary links to Lowe's. They earn us nothing today. If that ever changes it will say so here and on every page carrying one.
Products are chosen on whether they suit the job, never on commission. We do not accept payment from a manufacturer to feature a product, and no retailer has any say in what appears here or in what the calculator recommends.
Product recommendations are and will remain based on what your project actually needs. Where commercial relationships exist, they'll be labeled.
What's here, and what isn't yet
Five calculators are live — attic, walls, garage, crawl space, and spray foam. They share one calculation engine, so the numbers are consistent between them, but each asks the questions its own assembly actually turns on rather than relabelling the attic fields. Walls begin by asking whether the cavities are open; a crawl space checks for water and combustion safety before recommending anything; spray foam works in board feet because that is how it is quoted.
What is not here: we do not do the installation ourselves and we do not show live retail prices. We do pass quote requests to local insulation professionals and are paid for it, which is set out in our disclosure. Costs are national planning ranges with the assumptions documented on our methodology page.
We'd rather ship a small number of pages that are actually useful than a hundred that aren't.
Corrections
If a figure looks wrong, or an assumption doesn't hold for your region or construction type, tell us. Corrections to the underlying data are genuinely welcome — the methodology page exists partly so mistakes are findable.