Heat Pump vs Gas Furnace

Calculate what a hybrid or full heat pump saves per year compared with a gas furnace, and how many years it takes to pay back.

Natural gas for heating per year

Only the gas used for heating. If you only know your total use, take about three quarters of it. Use the kWh or therms from your bill: m³ here means Dutch gas.

Natural gas price

Your price per unit, including taxes.

Electricity price per kWh

Including taxes. A heat pump rate or your own solar power can make it lower.

Heat from the heat pump (%)

A hybrid (dual fuel) heat pump often supplies 60 to 70% of the heat, with the furnace doing the rest. A full heat pump is 100%.

Heat pump efficiency (SCOP)

How many kWh of heat the heat pump delivers per kWh of electricity over the heating season. Often 3 to 5 in the specifications; a large UK field trial measured a median of 2.8 in real homes.

Furnace efficiency (%)

A standard gas furnace reaches about 80% (AFUE), a condensing furnace 90% or more.

Cost after rebates

Purchase and installation, minus any grant, rebate or tax credit you qualify for. Replacing the furnace anyway? Then enter only the extra cost of the heat pump.

Fixed gas charges saved per year

Only if you stop using natural gas altogether: the fixed customer charge of your gas utility then goes away. Enter it per year; it differs by utility. For a hybrid: 0.

Show gas in

m³kWhtherms

The unit the calculator uses to show an amount of gas.

Pays back after

137 years and 6 months

Saving per year

$62.53

Cost with a gas furnace per year

$675.00

Cost with a heat pump per year

$612.47

Extra electricity per year

3,403 kWh

Less gas per year

450 therms

Please note: This is an example calculation, not financial advice. Personal circumstances, changes in rules and rates, and additional costs are not included. If in doubt, talk to a financial adviser.

Maintenance, the lifespan of the furnace and the heat pump, and changing energy prices are not included.

How this number is calculated

The blocks use your input. Change a value above and they update with it.

Step 1 · Heat your home needs

Natural gas for heating per year1,349.5445 m³ × Energy per m³ of natural gas9.77 × Furnace efficiency (%)80 ÷ Per100 =Heat your home needs10,548 kWh

Step 2 · Heat from the heat pump

Heat your home needs10,548 kWh × Heat from the heat pump (%)100 ÷ Per100 =Heat from the heat pump10,548 kWh

Step 3 · Electricity for the heat pump

Heat from the heat pump10,548 kWh ÷ Heat pump efficiency (SCOP)3.1 =Electricity for the heat pump3,403 kWh

Step 4 · Gas you still use

Natural gas for heating per year1,349.5445 m³ × 1 − Heat from the heat pump (%)100 ÷ Per100 =Gas you still use0 m³

Step 5 · Cost with a gas furnace

Natural gas for heating per year1,349.5445 m³ × Natural gas price$0.5002 per m³ =Cost with a gas furnace$675.00

Step 6 · Cost with a heat pump

Gas you still use0 m³ × Natural gas price$0.5002 per m³ + Electricity for the heat pump3,403 kWh × Electricity price per kWh$0.18 − Fixed gas charges saved per year$0.00 =Cost with a heat pump$612.47

Step 7 · Saving per year

Cost with a gas furnace$675.00 − Cost with a heat pump$612.47 =Saving per year$62.53

Step 8 · Pays back after

Cost after rebates$8,600.00 ÷ Saving per year$62.53 × Months per year12 =Pays back after137 years and 6 months

How the calculation works

Calculate what a heat pump saves compared with a gas furnace alone. Enter your gas use for heating, the energy prices, the efficiency of the heat pump and its cost, and see the saving per year and the payback period.

First the calculator figures out how much heat your home needs: the gas for heating times its energy content times the furnace efficiency. The heat pump supplies part of that heat, using electricity: the heat divided by its efficiency (SCOP). The rest of the heat still comes from gas. The cost with a heat pump is the remaining gas plus the electricity, minus the fixed gas charges if you stop using gas. The difference with the furnace alone is the saving; the cost divided by the saving is the payback period.

Formula

Heat (kWh) = gas in kWh × furnace efficiency. Heat pump electricity = heat × heat pump share ÷ SCOP. Cost with heat pump = gas × (1 − share) × gas price + electricity × electricity price − fixed charges saved. Saving = gas × gas price − cost with heat pump. Payback = cost ÷ saving.

Assumptions

Internally the calculator uses Dutch gas at 9.77 kWh per m³. kWh and therms convert exactly; UK and US gas holds more energy per m³.
Energy prices stay the same. If gas rises faster than electricity, the heat pump pays back sooner.
The SCOP is a seasonal average. With high flow temperatures and poor insulation it is lower.
Maintenance, a new furnace and the lifespan of the heat pump are not included.
The payback period is rounded to whole months, amounts to the cent.

Example calculations

The button fills in the calculator above, so you can carry on from there.

Hybrid heat pump

Pays back after
8 years and 7 months

Natural gas for heating per year 900 m³ · Natural gas price $1.35 per m³ · Electricity price per kWh $0.27 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Furnace efficiency (%) 90 · Cost after rebates $4,075.00 · Fixed gas charges saved per year $0.00
Full heat pump

Pays back after
9 years and 4 months

Natural gas for heating per year 900 m³ · Natural gas price $1.35 per m³ · Electricity price per kWh $0.27 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3.5 · Furnace efficiency (%) 90 · Cost after rebates $8,975.00 · Fixed gas charges saved per year $360.00
With your own solar power

Pays back after
6 years and 4 months

Natural gas for heating per year 900 m³ · Natural gas price $1.35 per m³ · Electricity price per kWh $0.15 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Furnace efficiency (%) 90 · Cost after rebates $4,075.00 · Fixed gas charges saved per year $0.00

Frequently asked questions

What does a heat pump save?

It depends mostly on the ratio between the electricity and gas prices. With 9,000 kWh of gas for heating at 0.08 per kWh, electricity at 0.26 and a full heat pump with SCOP 3, the saving is 126.00 a year, and a cost of 6,000 takes 47 years and 7 months to pay back. With a heat pump rate of 0.15 per kWh, the saving is 423.00 and the payback 14 years and 2 months.

Why is the saving sometimes small?

A heat pump uses electricity, which costs several times more per kWh than gas. If the electricity price divided by the gas price is close to the SCOP, the running costs are about the same. A higher SCOP, a cheaper electricity rate or your own solar power makes the difference.

What is the SCOP?

The seasonal efficiency: how many kWh of heat the heat pump delivers on average per kWh of electricity over the heating season. A SCOP of 4 means 4 kWh of heat from 1 kWh of electricity. The better the insulation and the lower the flow temperature of the heating, the higher the SCOP.

Hybrid or full heat pump?

A full heat pump replaces the furnace and lets you drop the gas supply and its customer charge, but costs more. A hybrid keeps the furnace for the coldest days, and gas for hot water. Compare both by changing the share of heat from the heat pump.

Which rebates are included?

None automatically: enter the cost after any rebate or tax credit you qualify for. Programs and amounts change, so check what applies to you.

Sources and checks

Sources

British thermal units (Btu) | U.S. Energy Information Administration (opens in a new tab)eia.gov · accessed October 5, 2026
Purchasing Energy-Efficient Boilers | US DOE (FEMP) (opens in a new tab)energy.gov · accessed October 6, 2026
Table CE4.6 Annual household site end-use consumption by fuel in the United States—averages, 2020 | U.S. Energy Information Administration (opens in a new tab)eia.gov · accessed October 6, 2026
U.S. Natural Gas Prices | U.S. Energy Information Administration (opens in a new tab)eia.gov · accessed October 6, 2026
Table Definitions, Sources, and Explanatory Notes | U.S. Energy Information Administration (opens in a new tab)eia.gov · accessed October 6, 2026
Energy conversion calculators | U.S. Energy Information Administration (opens in a new tab)eia.gov · accessed October 6, 2026
Table 5.3. Average Price of Electricity to Ultimate Customers: Total by End-Use Sector | U.S. Energy Information Administration (opens in a new tab)eia.gov · accessed October 6, 2026
Updated Buildings Sector Appliance and Equipment Costs and Efficiencies, Appendix A | U.S. Energy Information Administration (opens in a new tab)eia.gov · accessed October 6, 2026

How we check it

This calculator has 12 fixed checks: 8 calculations with a result that is fixed in advance, and 4 cases of invalid input that must be rejected. They all run automatically every time we publish; if one fails, the calculator does not go live.

See the calculations

Natural gas for heating per year 900 m³ · Natural gas price $1.35 per m³ · Electricity price per kWh $0.27 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Furnace efficiency (%) 90 · Cost after rebates $4,075.00 · Fixed gas charges saved per year $0.00 → Pays back after 8 years and 7 months
Natural gas for heating per year 900 m³ · Natural gas price $1.35 per m³ · Electricity price per kWh $0.27 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3.5 · Furnace efficiency (%) 90 · Cost after rebates $8,975.00 · Fixed gas charges saved per year $360.00 → Pays back after 9 years and 4 months
Natural gas for heating per year 600 m³ · Natural gas price $1.35 per m³ · Electricity price per kWh $0.27 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Furnace efficiency (%) 90 · Cost after rebates $4,075.00 · Fixed gas charges saved per year $0.00 → Pays back after 12 years and 10 months
Natural gas for heating per year 900 m³ · Natural gas price $1.35 per m³ · Electricity price per kWh $0.40 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Furnace efficiency (%) 90 · Cost after rebates $4,075.00 · Fixed gas charges saved per year $0.00 → Pays back after 13 years and 9 months
Natural gas for heating per year 900 m³ · Natural gas price $1.35 per m³ · Electricity price per kWh $0.15 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Furnace efficiency (%) 90 · Cost after rebates $4,075.00 · Fixed gas charges saved per year $0.00 → Pays back after 6 years and 4 months
Natural gas for heating per year 9,000 kWh · Natural gas price $0.08 per kWh · Electricity price per kWh $0.26 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3 · Furnace efficiency (%) 90 · Cost after rebates $6,000.00 · Fixed gas charges saved per year $108.00 → Pays back after 47 years and 7 months
Natural gas for heating per year 9,000 kWh · Natural gas price $0.08 per kWh · Electricity price per kWh $0.15 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3 · Furnace efficiency (%) 90 · Cost after rebates $6,000.00 · Fixed gas charges saved per year $108.00 → Pays back after 14 years and 2 months
Natural gas for heating per year 400 therms · Natural gas price $1.80 per therm · Electricity price per kWh $0.17 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3.5 · Furnace efficiency (%) 90 · Cost after rebates $8,000.00 · Fixed gas charges saved per year $0.00 → Pays back after 38 years and 6 months

Changes

October 6, 2026: Separate default values, units and sources for the UK and the US: gas in kWh or therms, energy prices, efficiency and the cost of a heat pump.
October 5, 2026: First version. Defaults follow the Ofgem price cap (gas 0.08, electricity 0.26, standing charge 108) and SCOP 3; the m³ option is now marked as Dutch gas. Sources added.

Last reviewed: October 9, 2026 · How we build and check our calculators