Insulation Savings Calculator
Annual heating cost saved by upgrading a surface's R-value
Estimate only: Savings are based on US national-average heating fuel prices for gas, electric, oil, and propane. Actual savings depend on your local utility rates and climate — check your bills for real prices.
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Quick summary
Enter the area, current and new R-value, your climate's heating degree days, and your heating fuel to estimate the annual heating cost saved by adding insulation. Upgrading a 1,000-sq-ft attic from R-11 to R-49 in a 5,000-HDD climate cuts heat loss by about 8.5 million BTU a year — roughly $130 with natural gas, more with electric or oil. It models conductive loss through that one surface (Q = Area × 24 × HDD × [1/R₁ − 1/R₂]); air sealing and other surfaces add further savings.
Reviewed by Simple Calculators TeamLast reviewed
How to use this calculator
- Enter the inputs requested by the calculator.
- Choose the units or options that match your situation and review the assumptions.
- Run or update the calculation to see the result.
- Review the result, breakdown, and formulas shown on the page.
- Check the inputs, units, dates, and limitations before saving or sharing the result.
Frequently asked questions
How much money does adding insulation save?
It depends on area, the R-value jump, your climate, and fuel. The savings come from reduced heat loss: doubling attic R-value roughly halves the heat escaping through it. Upgrading a poorly-insulated attic (R-11 to R-49) in a cold climate can save $100–$300+ a year — this calculator estimates your figure and the payback follows from the install cost.
What is R-value?
R-value measures resistance to heat flow — higher means better insulation. Heat loss through a surface is proportional to 1/R, so going from R-11 to R-22 cuts loss through it in half. The US Department of Energy recommends attic levels of R-38 to R-60 depending on climate zone.
What are heating degree days?
Heating degree days (HDD) measure how cold a location is over a year — the sum of daily degrees below 65°F. Mild climates run ~2,000–3,000 HDD; cold ones exceed 7,000. Higher HDD means more heating and bigger insulation savings. Look up your city's HDD for an accurate estimate.
Is attic insulation the best place to start?
Often, yes — heat rises, attics are usually the most under-insulated and the cheapest to improve, and the work is straightforward. Air sealing (gaps, ducts, around fixtures) frequently pays back even faster and complements insulation. This calculator handles one surface at a time; add rooms or surfaces separately.
Key terms
- R-Value
- Resistance to heat flow; higher R means less heat lost through a surface.
- Heating Degree Days
- A measure of how cold your climate is over the year (base 65°F).
- Heat Loss
- Energy escaping through a surface, proportional to area and 1/R.
- Air Sealing
- Closing gaps and leaks; complements insulation and often pays back fastest.
Methodology, sources & limitations
This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.
For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.