Free Insulation Calculator
Square footage, cost per square foot, and total project pricing for fiberglass batt insulation — calculated instantly from your building dimensions and delivery state. Free to use, no signup, no markup.
Price Calculator
Select your facing, R-value, square footage, and delivery state to see wholesale pricing instantly.
Add accessories and offer the Service Fee amount to complete order.
Five Quick Beats From Quote to Delivery
Facing, R-value, square footage, delivery state. Calculator returns wholesale + freight instantly.
Type your service-fee amount. Green badge means it clears our acceptable range for your order size.
Every calculator selection carries to the order page. Add address and contact info. Submit.
Payment Center takes PayPal, credit card, debit card, Venmo. Only line you pay Insulation Overstock.
Mill invoices you separately for material + freight with simple pay instructions. Shipping coordinator schedules delivery in 2 business days.
Full walkthrough on the homepage or in the founder’s 3-minute audio.
From Calculator Result to Delivered Order — The Four Steps
The calculator above is not a lead-generation form. It shows real numbers that turn into a real quote you can act on the same day. Here is what happens between typing your square footage and the freight truck showing up at your job site.
The calculator reveals the true factory rate
Once you pick a facing and R-value, the per-square-foot number displayed is the actual price a NAIMA-certified mill charges when it ships pallet quantities to a national distributor. That figure is not marked up, rounded up, or padded — it is the wholesale rate we invite you to verify against the mill directly. The freight-to-state line is the LTL carrier’s actual bill for the route.
You choose a service fee inside the posted range
Below the wholesale subtotal, the calculator posts an acceptable service-fee range for your specific order size. Small orders sit at 20 to 30 percent; commercial orders above $30,000 sit at 3 to 5 percent. You type any dollar amount inside that band. The badge turns green if the amount is inside the range, red if it is below the floor, so you know before submitting whether the offer will clear.
Insulation Overstock is paid only the service fee
After the offer is accepted, the calculator sends you to the order form, then to the Payment Center. You pay the service-fee amount directly to Insulation Overstock through PayPal, credit card, debit card, or Venmo. That single payment settles our involvement — sourcing the material, coordinating freight, and handling any support you need after delivery.
The certified fiberglass laminator is paid the wholesale cost
Within one business day of your service-fee payment clearing, the NAIMA-certified mill contacts you directly with instructions to pay the material and freight lines. You wire, ACH, or credit-card those amounts straight to the manufacturer. There is no reseller in the money flow — the mill is paid what the mill charges, and we do not touch the material portion of the transaction.
The result: the number in the calculator is the actual number you pay in total. No estimated freight that grows at checkout, no surprise handling fee on the invoice, no upsell for accessories that were already priced into the plan. What the calculator shows is what the project costs.
How to Calculate Your Insulation Needs
Not sure how many square feet your building requires? Enter your dimensions below and the estimator will calculate wall area, roof area, and total coverage including a 10% waste allowance.
Estimated Insulation Coverage
Scroll back up and enter this total into the price calculator to see your cost.
Understanding the Calculation
Wall area equals the building perimeter (twice the length plus twice the width) multiplied by the eave height. This gives you the total vertical surface that needs insulation coverage.
Roof area starts with the building footprint (length times width) and adjusts for pitch. Steeper roofs have more surface area than the footprint alone because the panels run at an angle from eave to ridge. The slope factor formula accounts for this additional material.
The 10% waste factor covers overlap at seams, cuts around framed openings such as doors and windows, and material lost during trimming. Buildings with large overhead doors may need less material, while complex rooflines may need more.
Wall Insulation Calculator (Square Feet)
If you only need to calculate wall coverage — for example, when the roof is already insulated or you are insulating walls separately during a retrofit — the math is straightforward. Multiply the perimeter of your building by the eave height to get total wall square footage, then subtract roughly 100 square feet for a typical service door and small window.
For a 30 ft × 50 ft pole barn with 14-foot eaves: perimeter is 160 feet, multiplied by 14 = 2,240 sq ft of wall area. Subtract about 100 sq ft for openings and add the 10% waste factor and you arrive at approximately 2,355 sq ft of wall insulation needed.
Drop your wall square footage straight into the price calculator at the top of this page to see wholesale fiberglass pricing per square foot for any R-value and facing combination.
Batt Insulation Calculator for Fiberglass Rolls
The calculator on this page is built specifically for fiberglass batt and roll insulation — the format used in nearly every metal building, pole barn, and commercial structure. Batt insulation is sold in pre-cut widths (4 ft, 5 ft, 6 ft, and the 8 ft option in WMP-30) and standard roll lengths (30 ft and 50 ft). The square footage you enter translates directly to roll quantity at order time.
Compared to blown-in or spray-foam options, batt fiberglass is the most predictable insulation type to estimate. There is no overspray loss, no settling depth to calculate, and no special equipment rental cost to factor in. Square footage in equals square footage out, plus a small waste allowance.
The pricing the calculator returns matches what professional installers and large bulk buyers pay because we publish the actual factory-direct rate — not a marked-up retail number padded with margin.
How Much Insulation Do I Need for 1,200 Sq Ft?
A 1,200 square foot building — the size of a typical hobby shop, two-car garage with workspace, or 24x50 pole barn — needs roughly the following insulation quantity depending on which surfaces you are covering:
- Wall surface (assuming 9 ft eaves on a 24x50): ~1,332 sq ft at $0.90/sq ft = $1,199
- Ceiling surface (1,200 sq ft) at R-25: 1,200 sq ft at $1.13/sq ft = $1,356
- Material subtotal: $2,555
- Freight (typical state): ~$445
- Wholesale subtotal: ~$3,000
- Acceptable service fee offer: ~$450 to $900 (15% to 30%)
- Total Delivered: ~$3,450 to $3,900 depending on your offer
For a single-surface install (walls only or ceiling only), divide the relevant line in half. The calculator above handles any building size from a 100 sq ft shed up to a 40,000 sq ft warehouse with the same itemized output.
For a 1,200 sq ft conditioned space heated and cooled year-round, R-19 walls and R-25 ceiling is the IECC-compliant baseline in most climate zones. For cold climates (Zones 5+), step the ceiling up to R-30. For warm climates (Zones 1-2), R-13 walls are often sufficient.
Insulation Cost Per Square Foot
Factory-direct pricing per square foot for every facing and R-value we sell. Use these numbers to sanity-check the calculator output above.
| Facing | R-8 | R-13 | R-19 | R-25 |
|---|---|---|---|---|
| VR-R Plus | $0.48 | $0.65 | $0.90 | $1.13 |
| WMP-10 | $0.54 | $0.71 | $0.96 | $1.19 |
| WMP-30 | $0.54 | $0.71 | $0.96 | $1.19 |
| WMP-50 | $0.54 | $0.71 | $0.96 | $1.19 |
| VR Black | $0.52 | $0.69 | $0.94 | $1.17 |
| WMP-10 Black | $0.58 | $0.75 | $1.00 | $1.23 |
| WMP-50 Black | $0.58 | $0.75 | $1.00 | $1.23 |
Prices reflect current wholesale rates and update as manufacturer pricing changes. R-10 and R-11 are also available — pricing falls between R-8 and R-13 for each facing. Add freight ($445–$745 by state) and your offered service fee for the project total.
Attic Insulation Calculator Note
This calculator is built for fiberglass batt and roll insulation, not blown-in cellulose or loose-fill fiberglass. If you are insulating an attic with batt rolls (a common approach when the attic has open joist bays or stick-framed trusses), the calculator works exactly the same way: multiply length by width to get the floor area, then enter that square footage and select your R-value.
For attics in cold climate zones (5 and above), R-38 to R-49 is the typical recommendation. Single-layer batts top out at R-25, so attic builds often involve cross-layering two batts or combining a batt layer underneath with blown-in over the top. The calculator handles the batt layer; for blown-in, you would need to source that material separately from a local supplier.
R-Value Guide
R-value measures thermal resistance. Higher numbers mean better insulating performance. Use this table to match R-value to your application and climate.
| R-Value | Thickness | Recommended Application |
|---|---|---|
| R-8 | 2.5" | Light-duty walls, interior partitions |
| R-10 | 3.0" | Standard walls in mild climates |
| R-11 | 3.5" | Standard 2x4 wall cavities |
| R-13 | 3.625" to 4" | Standard walls, moderate climates |
| R-19 | 6.0" | Walls and ceilings, cold climates |
| R-25 | 8.0" | Roofs, ceilings, extreme cold climates |
R-Value Recommendations by Climate Zone
The Department of Energy divides the United States into climate zones numbered 1 through 7. Each zone has recommended minimum R-values for walls and roofs to achieve energy-efficient performance.
Zones 1 – 2 (Hot Climates)
Southern states such as Florida, Texas, Arizona, and coastal Gulf regions. Primary insulation goal is keeping heat out and reducing cooling costs.
- Walls: R-11 to R-13
- Roof/Ceiling: R-19 to R-25
Zones 3 – 4 (Mixed Climates)
Mid-Atlantic, Southeast interior, and lower Midwest regions. Buildings face both heating and cooling demands across seasons.
- Walls: R-13 to R-19
- Roof/Ceiling: R-25
Zones 5 – 7 (Cold Climates)
Northern states, upper Midwest, and mountain regions. Winters are long and heating costs dominate energy budgets. Maximum R-value delivers the best return on investment.
- Walls: R-19 to R-25
- Roof/Ceiling: R-25
Tip: The roof is the single largest source of heat gain in summer and heat loss in winter. If budget forces you to choose, invest in maximum roof R-value first and use a lower R-value on walls. This delivers the best energy efficiency per dollar spent.
Insulation Calculator FAQ
Start with your building dimensions. Measure the exterior length, width, and eave height. Multiply the perimeter (2 x length + 2 x width) by the eave height to get wall area. For the roof, multiply the building footprint (length x width) by the slope factor for your pitch. Add wall and roof areas together and apply a 10% waste allowance. Use the building estimator above for an instant calculation.
R-value selection depends on your climate zone and how the building will be used. Mild climates (zones 1-2) typically require R-11 to R-13 in walls and R-19 or higher in roofs. Cold climates (zones 5-7) benefit from R-19 in walls and R-25 in roofs. Conditioned spaces such as workshops and offices should use the highest R-value you can accommodate. Unconditioned storage buildings may need only minimal insulation for condensation control.
Wholesale fiberglass insulation ranges from approximately $0.46 to $1.23 per square foot depending on the facing type and R-value. VR-R Plus is the most economical white-faced option starting at $0.46 per square foot for R-8. Higher R-values and premium facings such as WMP-50 cost more per square foot but deliver greater thermal performance and durability. Use the price calculator at the top of this page to see exact pricing for your configuration.
Yes. When you select your delivery state, the calculator adds the freight charge to your estimate. Shipping typically ranges from $395 to $695 depending on distance from the manufacturing plant. The calculator also factors in the flat service fee based on your total material cost, giving you a complete delivered price estimate.
There is no hard minimum order requirement. Orders under $1,000 in material cost carry a $150 service fee. As the order size increases, the service fee scales proportionally but remains a flat, published rate. Most building projects for metal buildings and pole barns naturally exceed the $1,000 threshold. See our order page for the complete fee schedule.
Once you have your estimate, visit the order page and submit your building details, preferred facing, R-value, and delivery location. Our team reviews every order request to confirm quantities and pricing before processing. You can also call us at 1-800-593-4012 to place an order directly with a specialist who can walk you through the options.
Ready to Order Your Insulation?
Take your estimate and request a wholesale quote. We verify quantities, confirm pricing, and ship factory-direct to your site.