This calculator vs. a flat price-per-square-foot special

"$1.50 a foot" is not a price for an attic — it is a price for one specific R-value delta, product, and scope, quietly applied to every attic that walks in the door.

What a flat per-foot rate is

A flat rate is the fastest way to quote: multiply the attic's square footage by a number and read off a price. Homeowners shop it because it is easy to compare between bids, and crews use it because it needs no takeoff. It is also the rate a customer holding a postcard or a competitor's website will ask you to match.

The number behind it was set for one job — one product, one starting R-value, one target, no removal, no unusual penetrations — and then reused for every attic afterward, whether or not the next attic looks anything like the one the rate was built on.

What this calculator is

This page keeps no account and sends nothing to a server. You enter each attic section's area, existing R-value, and target R-value, the product's R-per-inch and bag yield, the air-sealing penetrations and baffles, and your loaded labor and overhead. It converts the R-value delta into inches and bags per section, adds the blow, air-seal, and removal hours separately, and returns a walk-away price below which the job loses money — for this attic, not a generic one.

What a flat per-foot rate does	What this calculator does instead
Charges the same $/sq ft whether the attic is going from R-30 to R-38 or from R-13 to R-49 — a several-times difference in bags for the same floor area.	Converts each area's existing-to-target R-value into inches added, then bags, from the product's own R-per-inch and cubic feet per bag.
Prices "the attic" as one blow, with no separate line for penetrations, a hatch dam, or baffles at the eaves.	Times air sealing at minutes per penetration and baffles at their own rate, so that labor shows up instead of being absorbed into the blow or skipped.
Assumes a clean blow over existing material, so a job needing removal of wet or contaminated fill gets quoted the same as one that does not.	Adds removal hours per square foot plus a dumpster line only when that scope is turned on, so the two jobs price differently.
Bakes payroll burden into a round "labor rate" nobody re-derives, so the rate quietly drifts from the crew's real loaded cost.	Loads the entered hourly wage by the entered payroll-burden percentage every time, so the labor cost tracks the actual burden rather than a memorized rate.
Gives the crew a price to quote, not a number to check a quote against.	Reports the walk-away price, the effective hourly rate, and how much of labor is air sealing versus blowing, so a shopped price can be scored against real cost before the crew commits to it.

A flat rate is not wrong because it is simple — it is wrong when it is applied outside the one job it was built for, and nothing about a postcard rate tells you when that has happened. This calculator does not replace judgment about your market; it replaces the arithmetic a flat rate skips.

Common questions

Why does a flat price per square foot get attic insulation wrong?

Because bags come from how much R-value has to be added, not from the floor area alone. An attic already at R-30 going to R-38 needs a fraction of the fill that the same square footage at R-13 going to R-49 needs. A flat rate charges both the same and is wrong on one of them every time.

What does a flat rate usually leave out entirely?

Air sealing and baffles. Foam at penetrations, a hatch dam, and baffles at the eaves are their own hour stack separate from the blow itself, and a rate built around "square feet of attic" has nowhere to put that labor. Crews who price off the blow alone and figure sealing in for free are short before the truck leaves the yard.

What happens when the existing fill has to come out first?

A flat installed rate assumes a clean blow over existing material. Wet, settled, or rodent-contaminated fill means removal hours plus a dumpster before a single bag goes in, and a rate that never asked the question charges the same price for a job that takes twice as long.

Is a flat rate ever the right way to quote?

For a narrow band of near-identical jobs — same product, same starting R-value, same target, no removal — a flat rate can land close. The risk is applying it outside that band without noticing, because the postcard rate does not know which band a given attic is in and neither does the crew until they measure it.

Does this calculator know what to charge in my market?

No. It has no data on local rates, bag prices, or what competitors charge. It takes the wage, bag cost, and overhead you enter and turns them into a walk-away price for the areas, R-values, and scope you describe — the arithmetic a flat rate skips, not a market survey.

Nothing here says or implies that quoting a flat rate per square foot is a bad-faith practice — it is a common, honest shortcut that works until the job stops matching the one the rate was set on. This page describes where that shortcut breaks down, not a fault in anyone who uses it.

Open the Attic Insulation Bid Calculator and price your own job.