How much attic insulation do I need?

ENERGY STAR recommends R-49 to R-60 for an uninsulated attic in zones 2 to 8, and R-30 in zone 1. See the table for your zone.

How many bags of insulation do I need?

Divide the area by the sq ft per bag printed on the label at your target R-value. Coverage changes with the R-value, so use the right row.

What climate zone am I in?

Zones are set by county. Ask your building department to confirm yours.

Is the ENERGY STAR figure the code minimum?

No. It is a retrofit recommendation. New construction and permitted work follow your adopted energy code.

HyreRemodel tools

Insulation calculator

Pick your climate zone and where you are insulating, then enter the area and the coverage per bag from the label.

An insulation calculator looks up the recommended R-value for your climate zone, then divides the area by the coverage per bag. ENERGY STAR recommends R-49 to top up an attic with 3–4 in of existing insulation in zones 4 to 8. At 40 sq ft per bag, 1,000 sq ft needs 25 bags.

Work out your insulation

Arithmetic on your figures. Nothing is stored or emailed.

— Recommended R-value

— To buy

— Area

What this assumed —

ENERGY STAR retrofit figures. Your energy code governs permitted work.

Recommended insulation R-values by climate zone

ENERGY STAR publishes recommended R-values for adding insulation to existing wood-framed homes.

Zone	Attic, uninsulated	Attic, 3–4 in existing	Floor
Zone 1	R-30	R-25	R-13
Zone 2	R-49	R-38	R-13
Zone 3	R-49	R-38	R-19
Zones 7 and 8	R-60	R-49	R-38
Zones 4A and 4B	R-60	R-49	R-19
Zones 4C, 5 and 6	R-60	R-49	R-30

ENERGY STAR (US EPA), retrieved 2026-10-22. Retrofit recommendations, not code minimums. New work is governed by your adopted energy code (IECC Section R402 where adopted).

Worked example

Topping up an attic in zone 5

Target

An attic with 3–4 in of old insulation in zone 5: ENERGY STAR recommends R-49.

Bags

1,000 sq ft of attic floor. If the bag label says one bag covers 40 sq ft at R-49, buy 25 bags. Labels differ, so read yours.

Bags = area ÷ the label’s sq ft per bag at the target R-value, rounded up.

How to find your climate zone

Your building department can tell you your climate zone. The zone sets which row of the table applies.

Seal before you insulate. Air leaks through the ceiling bypass insulation. See air sealing and vapor retarder.

Before you disturb an attic

Vermiculite insulation, the gray-brown pebbly kind, may contain asbestos. EPA recommends leaving it undisturbed; removal should be done by a trained and accredited asbestos abatement contractor.

Keep insulation clear of hot surfaces such as chimneys, flues and recessed lights not rated for contact. Have a licensed pro confirm the clearances.

What the insulation calculator leaves out

The insulation calculator gives no price. Multiply the bags by the price on the shelf or the bid. Walls are not in the ENERGY STAR table as a single figure; your installer sizes them to the cavity.

For the rooms around it, see attic conversion and basement finishing, or plan your remodel with us.

Questions this calculator answers

How much attic insulation do I need?: ENERGY STAR recommends R-49 to R-60 for an uninsulated attic in zones 2 to 8, and R-30 in zone 1. See the table for your zone.
How many bags of insulation do I need?: Divide the area by the sq ft per bag printed on the label at your target R-value. Coverage changes with the R-value, so use the right row.
What climate zone am I in?: Zones are set by county. Ask your building department to confirm yours.
Is the ENERGY STAR figure the code minimum?: No. It is a retrofit recommendation. New construction and permitted work follow your adopted energy code.

Sources and methodology

Figures dated October 22, 2026. Last reviewed August 16, 2026.

Recommended home insulation R-values (ENERGY STAR (US EPA), retrieved October 22, 2026). Retrofit R-values by climate zone.
My attic has vermiculite insulation in it. Am I at risk? (US Environmental Protection Agency, retrieved October 22, 2026). Vermiculite attic insulation.

Attic conversion Insulating a finished attic.
Drywall calculator Closing the walls after.
Basement finishing Insulating below grade.
Whole-home renovation When every wall is open.

Plan Your Remodel Back to the home page