Heat Pump Savings Calculator
Use this heat pump savings calculator to compare modeled heating costs before and after replacing a natural-gas furnace or electric resistance system. Enter your heating use, energy prices and seasonal efficiency assumptions. Include backup heating, cooling changes and maintenance to see annual savings and the payback on an additional installation cost.
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Report a calculation issue Heat Pump Savings Calculator: purpose and method
Use this heat pump savings calculator to compare modeled heating costs before and after replacing a natural-gas furnace or electric resistance system. Enter your heating use, energy prices and seasonal efficiency assumptions. Include backup heating, cooling changes and maintenance to see annual savings and the payback on an additional installation cost.
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Method and test recordFormula v1.0.1
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- Not recorded
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- CalculatorGeek
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- CalculatorGeek Editorial Team
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- Not recorded
- Next source review
- Not scheduled
- Definition fixtures
- 3 configured scenarios
- Published examples
- 3 shown below
Recorded method
No tool-specific review method has been recorded.
These records describe the published model and reference tests. A test-case count is not a certification of every possible input or an independent specialist review. Editorial policy
Known limitations
Method sources
Latest model update
2026-10-28 - Created from finished package copy and deterministic contract.
Reference inputs and expected results
Up to 12 examples from the configured definition fixtures are shown. Expected values use the stated output units; invalid inputs are intended to be rejected.
| Case | Inputs | Expected result |
|---|---|---|
| Gas to heat pump without backup | Therms: 1000; Old Efficiency: 0.8; Gas Rate: 1.5; Seasonal heat-pump COP: 3; Backup Fraction: 0; Electric Rate: 0.15; Incremental Cost: 4000 | Heat Kwh: 23446.658851114; New Kwh: 7815.5529503712; New Cost: 1172.3329425557; Annual Saving: 327.66705744431; Simple Years: 12.207513416816 (allowed numeric tolerance: 1.0E-6) |
| Backup heat reverses savings | Therms: 1000; Old Efficiency: 0.8; Gas Rate: 1.5; Seasonal heat-pump COP: 3; Backup Fraction: 0.2; Electric Rate: 0.15; Incremental Cost: 4000 | New Kwh: 10941.77413052; New Cost: 1641.266119578; Annual Saving: -141.26611957796; Simple Years: null (allowed numeric tolerance: 1.0E-6) |
| Resistance baseline with known ratio | Old Heating Kwh: 12000; Old Efficiency: 1; Seasonal heat-pump COP: 3; Electric Rate: 0.2; Backup Fraction: 0; Incremental Cost: 4800 | New Kwh: 4000; Annual Saving: 1600; Simple Years: 3 (allowed numeric tolerance: 1.0E-6) |
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On this page
Use heating energy, not the whole utility bill
For a gas comparison, enter annual therms used for space heating. Exclude gas used for water heating, cooking or other appliances. Monthly bills or an energy assessment may help separate these loads; using the entire annual gas total would overstate the heat pump’s replacement benefit.
For electric resistance heating, enter the electricity attributable to heating. Keep cooling and other household electricity separate. The calculator compares the same estimated amount of useful heat in both scenarios, rather than assuming equal bills mean equal heating needs.
Enter the existing system’s overall seasonal delivered efficiency. It represents the portion of purchased fuel energy that becomes useful heat in your home. Equipment ratings, duct losses and actual operating conditions are not always interchangeable, so use an assessment appropriate to the comparison.
Seasonal COP and backup heat
The heat pump’s seasonal coefficient of performance, or COP, is modeled as useful heat delivered divided by electricity consumed over the season. A COP of 3 means the scenario delivers three units of heat for each unit of electricity. This is an entered assumption, not a promise based on the product name.
A single warm-weather test rating may not represent winter operation. DOE’s residential heat-pump guidance explains why climate and system characteristics matter to performance.
Enter the share of heating supplied by electric resistance backup. The model gives that portion a COP of 1. It calculates the remaining heat at your heat-pump COP. Avoid counting the same backup electricity again inside a seasonal COP that already includes it.
How the heating-cost calculation works
The U.S. Energy Information Administration lists 100,000 Btu per therm and a rounded 3,412 Btu per kilowatt-hour. Using those conversion factors:
Useful heat in kWh = heating therms × 100,000 ÷ 3,412 × delivered efficiency.
Without backup heat, heat-pump electricity is useful heat divided by COP. With electric backup, each portion is calculated separately. Multiply the resulting electricity use by your marginal electricity price, including applicable variable charges.
Compare that cost with your current heating cost. Add entered cooling savings and subtract any increase in maintenance. Count gas service fees as avoided only if the gas account can actually be closed; keeping a gas water heater may mean those charges remain.
Worked example: switching from gas
Assume 1,000 annual heating therms, 80% delivered efficiency, gas at $1.50 per therm, a seasonal heat-pump COP of 3 and electricity at $0.15/kWh. There is no backup heat, cooling change or maintenance difference in this illustrative example.
Useful annual heat is approximately 23,446.66 kWh. The heat pump requires about 7,815.55 kWh, costing $1,172.33. Current gas heating costs $1,500, so modeled annual savings are $327.67.
If the heat-pump installation costs $4,000 more than the alternative replacement after confirmed immediate incentives, simple incremental payback is approximately 12.21 years. This compares the additional investment with additional savings, rather than charging the heat pump for a replacement you would need anyway.
Now change the electric-backup share to 20% while keeping the other inputs. Modeled electricity cost rises to about $1,641.27, making annual savings negative $141.27. That is why backup and seasonal performance assumptions can change the conclusion.
Installation cost and incentives
Enter a real installation quote, including any electrical or duct work, and compare it with a real alternative-replacement quote. No equipment size or local installation price is inferred from floor area.
Do not automatically subtract the former federal heat-pump credit from a 2026 installation. IRS guidance limits that credit to qualifying improvements through 2025. Confirm any state, local or utility assistance and distinguish later reimbursements from immediate funding.
If financing is required, compare the repayment costs with the personal loan calculator or examine a HELOC payment scenario. Operating savings do not automatically cover financing payments.
Frequently asked questions
Does a heat pump always cost less to run than gas?
No. The result depends on gas and electricity prices, delivered efficiency, seasonal COP and backup use. Compare the same heating demand under both scenarios.
Can I use this result to select equipment size?
No. Annual energy comparison does not replace a heating/cooling load calculation or an installer’s assessment of distribution and electrical requirements.
Why is there no positive payback number?
If annual savings are zero or negative, an additional purchase cost is not recovered through the modeled savings. If the upgrade has no additional cost, the result says so instead of forcing a ratio.
Does the calculator handle oil, propane or a gas backup system?
This version covers natural gas or electric resistance replaced by a heat pump with optional electric resistance backup. Other fuels and hybrid gas operation need a different energy and tariff model.
Enter your heating use and actual energy prices, then compare expected performance with a lower-COP or higher-backup scenario.