Heat Pump vs. Gas Furnace Cost Calculator: Finding Your Temperature Crossover Point

If you are comparing a heat pump with a gas furnace, the answer is not one fixed outdoor temperature. The cheaper system depends on your electricity price, gas price, furnace efficiency, heat pump performance at that temperature, backup heat settings, and the way your home loses heat.

A useful heat pump vs. gas furnace calculator does not start with a rule like "switch at 35 degrees." It starts with cost per unit of heat delivered into the house. Once you know that number, you can estimate when the heat pump is cheaper, when the furnace is cheaper, and when a dual-fuel setup deserves a closer look.

This article is a planning framework, not tax, engineering, contractor, or utility-rate advice.

The Short Answer: There Is No Universal Crossover Temperature

A heat pump can be cheaper than a gas furnace in one home and more expensive in another home on the same day.

The difference usually comes down to four inputs:

• Electricity price in dollars per kilowatt-hour.
• Natural gas price in dollars per therm.
• Heat pump efficiency at the outdoor temperature being tested.
• Gas furnace efficiency, usually shown as AFUE.

If electricity is relatively inexpensive and the heat pump is still operating at a strong coefficient of performance, the heat pump can have the lower operating cost. If gas is cheap, electricity is expensive, or the heat pump's efficiency drops sharply in cold weather, the furnace may be cheaper for that portion of heating.

That is why the same outdoor temperature can lead to different answers in different states, utility territories, homes, and equipment combinations.

What "Crossover Temperature" Means

The crossover temperature is the point where two heating options cost about the same to produce delivered heat.

For a dual-fuel homeowner, the practical question is:

At what outdoor temperature should the system prefer the heat pump, and when should it rely on the gas furnace?

That sounds like a thermostat setting, but the economics are not only about temperature. The outdoor temperature matters because heat pump performance changes as outdoor conditions change. Your local prices matter because the heat pump buys energy in kilowatt-hours while the furnace buys energy in therms of gas.

There is also a separate HVAC design concept called the balance point. DOE explains that the balance point is the outdoor temperature where a heat pump's capacity matches the home's heating load. Below that point, auxiliary heat may help meet the load. That is related to comfort and capacity, not exactly the same as the economic crossover point.

In plain language:

• Balance point asks whether the heat pump can keep up with the house.
• Economic crossover asks which heat source is cheaper at a given performance level.

Both matter, but they are not interchangeable.

COP vs. AFUE In Plain English

Heat pumps and gas furnaces use different efficiency language.

Coefficient of performance, or COP, describes how much heat a heat pump delivers for each unit of electricity it uses. A COP of 3 means the heat pump delivers about three units of heat for each unit of electric energy consumed. DOE describes this advantage as coming from heat transfer rather than direct fuel conversion.

AFUE, or annual fuel utilization efficiency, describes how much fuel energy a furnace turns into usable heat over a season. A 95% AFUE furnace turns about 95% of the fuel energy into useful heat, with the rest lost through venting and other system losses.

That difference matters. A high-efficiency gas furnace can be close to 100% efficient, but it is still converting fuel into heat. A heat pump moves heat, so its COP can be above 1. That does not automatically make it cheaper. It means you need to translate both systems into the same unit before comparing cost.

The Cost-Per-Heat Formula

To compare a heat pump and a gas furnace, convert both to cost per million Btu of delivered heat.

EIA's energy conversion calculator lists 1 kilowatt-hour as 3,412 Btu and 1 therm as 100,000 Btu. That means 1 million Btu equals about 293.1 kilowatt-hours, and 1 million Btu equals 10 therms.

Use these formulas:

heat pump cost per million Btu delivered =
(electricity price per kWh x 293.1) / heat pump COP

gas furnace cost per million Btu delivered =
(gas price per therm x 10) / furnace AFUE

Use AFUE as a decimal. A 95% AFUE furnace becomes 0.95.

You can also solve for the break-even heat pump COP:

break-even COP =
(electricity price per kWh x 293.1 x furnace AFUE) / (gas price per therm x 10)

If the heat pump's real COP at a given outdoor temperature is above that break-even COP, the heat pump is cheaper for that unit of heat. If it is below that break-even COP, the gas furnace is cheaper for that unit of heat.

That still does not tell you whether the system is properly sized, whether your ducts are right, whether backup heat is configured well, or whether your contractor's quote is reasonable. It only compares fuel operating cost under the assumptions entered.

Example: Heat Pump vs. Gas Furnace At Different COP Levels

Here is a hypothetical scenario. Use your own rates before making any decision.

Assumptions:

• Electricity price: $0.18 per kWh.
• Natural gas price: $1.50 per therm.
• Gas furnace efficiency: 95% AFUE.
• Heat pump COP: tested at 3.5, 3.0, 2.5, and 2.0.
• Maintenance, service fees, utility fixed charges, demand charges, and equipment cost: excluded.

First, calculate the gas furnace cost:

($1.50 x 10) / 0.95 = $15.79 per million Btu delivered

Then calculate the heat pump cost at several COP levels:

The break-even COP in this example is about 3.34.

($0.18 x 293.1 x 0.95) / ($1.50 x 10) = 3.34

That means the heat pump needs to operate above roughly COP 3.34 to beat the furnace on fuel cost in this specific scenario. If the same homeowner paid a lower electric rate, a higher gas rate, or used a different furnace efficiency, the answer would change.

This is the point of the calculation. It gives you a way to test the claim instead of accepting a universal switchover temperature.

Why Outdoor Temperature Changes Heat Pump Economics

An air-source heat pump extracts heat from outdoor air and moves it indoors. DOE notes that modern air-source heat pumps can provide efficient heating and cooling, and recent technology improvements have made them viable in regions with extended subfreezing periods.

That does not mean every heat pump has the same cold-weather performance.

As outdoor temperature drops, a heat pump may need to work harder to deliver the same amount of heat. Some systems maintain capacity and efficiency better than others. ENERGY STAR notes that many certified air-source heat pumps are capable of low-temperature performance, and cold-climate models are tested for performance at low outdoor temperatures.

For your crossover math, the most useful data is not a single seasonal rating. It is the manufacturer's performance table for the exact model or system match being proposed. Ask your contractor for heating capacity and efficiency at outdoor temperatures relevant to your climate, such as 47 degrees, 17 degrees, 5 degrees, or the local design temperature.

Use those COP values in the formula rather than assuming one COP applies all winter.

Why Local Energy Prices Can Change The Answer

Heat pump economics are sensitive to local rates.

The same heat pump can look stronger in an area with high gas prices and moderate electric rates. It can look weaker in an area with low gas prices and high electric rates. Time-of-use electric pricing, seasonal gas rates, fixed monthly charges, and delivery fees can also change the real bill impact.

For a first pass, use the all-in prices from your bills:

• For electricity, divide the total variable electric charges by kWh used if your bill makes that clear.
• For gas, divide the variable gas charges by therms used if your bill makes that clear.
• Keep fixed monthly customer charges separate unless the upgrade changes whether you keep the service.

Do not use a national average when you have your own bill. Averages can be useful for education, but your thermostat runs on your utility prices.

What Dual-Fuel Homeowners Should Watch

A dual-fuel system pairs a heat pump with a gas or oil furnace. ENERGY STAR describes dual fuel as a setup that can use each heating source based on cost and environmental factors.

That flexibility is useful only if the switchover logic is set thoughtfully.

Watch these issues:

• The switchover temperature should be based on your rates, equipment, and comfort needs, not a generic rule.
• Backup heat settings can change operating cost.
• Thermostat setbacks can trigger backup heat in ways that undercut savings.
• A heat pump that is too small may rely on backup heat more often.
• A heat pump that is poorly installed may miss its rated performance.
• A rate change can make last year's switchover setting outdated.

DOE cautions that backup heating systems, including electric resistance or strip heat, are usually more expensive to operate because they are less efficient. That does not mean backup heat is bad. It means it should be understood, configured, and included in your cost expectations.

For dual fuel, ask the contractor to explain:

• The proposed lockout or switchover temperature.
• Whether the control is based on outdoor temperature, utility rate, equipment capacity, or comfort.
• How the system handles defrost and auxiliary heat.
• Whether the thermostat settings can be adjusted later if rates change.

What The Energy Bill HQ Heat Pump Savings Estimator Can And Cannot Do

The Energy Bill HQ Heat Pump Savings Estimator is designed for annual planning, not room-by-room HVAC design.

It compares:

• Current annual heating and cooling cost.
• Estimated annual cost after the heat pump upgrade.
• Installation cost.
• Confirmed rebates or incentives entered by the user.

The calculator then estimates annual savings and simple payback:

annual savings = current annual cost - expected annual cost after upgrade

simple payback = net install cost / annual savings

The current site defaults are planning assumptions, not market promises. The public methodology and live estimator frame the heat pump model around a standard 40% efficiency-gain assumption and an automated installation-cost baseline that the homeowner should replace with a real quote. In the live calculator, the after-upgrade annual cost is estimated as 60% of current annual cost when the user enters a baseline.

Use that as a first pass. Then replace the defaults with your own bill history, quote, confirmed incentives, and any contractor-provided performance data.

The estimator does not replace:

• A Manual J load calculation.
• Equipment selection or Manual S design.
• Duct evaluation.
• Contractor quote review.
• Local tariff modeling.
• Maintenance cost planning.
• Fuel-switching analysis.
• Tax or rebate eligibility review.

As of April 17, 2026, IRS OBBB guidance says the federal Energy Efficient Home Improvement Credit under Section 25C is not allowed for property placed in service after December 31, 2025. For current 2026 planning, do not include a federal heat pump credit unless you have confirmed current official guidance for your specific project.

Internal link: /heat-pump-savings-estimator

How To Run Your Own First-Pass Estimate

Use this sequence before comparing contractor proposals.

1. Pull your electric and gas bills.
2. Find your current all-in variable electricity price per kWh.
3. Find your current all-in variable gas price per therm.
4. Write down the AFUE of your existing or proposed furnace.
5. Ask for the proposed heat pump's heating performance at relevant outdoor temperatures.
6. Calculate the break-even COP.
7. Compare the model's actual COP at each temperature with the break-even COP.
8. Use the Energy Bill HQ Heat Pump Savings Estimator to translate the annual scenario into simple payback.
9. Keep confirmed rebates separate from rumored rebates or stale incentive pages.
10. Ask for a Manual J-based sizing explanation before treating the proposal as final.

The math does not have to be perfect to be useful. It just needs to be honest about the assumptions.

Bottom Line

A heat pump is not automatically cheaper than a gas furnace, and a gas furnace is not automatically cheaper than a heat pump. The answer changes with COP, AFUE, local prices, outdoor temperature, backup heat, and installation quality.

The safest first-pass method is to compare cost per million Btu delivered, then use an annual estimator to see whether the upgrade economics still make sense after installation cost and confirmed incentives.

Use the crossover math to pressure-test claims. Use the Energy Bill HQ Heat Pump Savings Estimator to model annual operating savings. Use a qualified HVAC contractor for sizing, equipment selection, and installation details.