Heat Pump Savings Calculator: Why Three Contractors Couldn't Show Me the Math

Three contractors came to my house.

All of them said the same thing about heat pumps. Efficient. Modern. It'll pay for itself. Not one of them could tell me how long that payback would actually take. One guy said a few years. Another said it depends on usage. The third just smiled and talked about rebates.

I smiled back. Then I asked him what my current furnace cost per year to run. He didn't know. I asked what a heat pump would cost with my electricity rate. He said, less. I said, how much less. He changed the subject to installation timelines.

I'm not saying he was lying. I'm saying he was selling. And selling runs on hope, not math.

My current setup is natural gas. Eighty percent efficient, which sounds good until you realize twenty percent of what I pay for just disappears into the air. The furnace is loud, reliable, and expensive. I added up a full year of gas bills and divided by the therm price.

Seven hundred therms. At one dollar twenty per therm, that's eight hundred forty dollars a year just for heat. That doesn't include the standing charge, the maintenance, the filter I forget to change.

I started looking for a heat pump savings calculator that used real numbers. Most of what I found asked for my state and gave me a national average. I don't live in an average. I live in my house, with my rates, with my insulation that could be better.

So I built one. You enter your fuel price, your electricity rate, your annual usage or cost, and the heat pump efficiency which is called COP. It shows you the operating cost, the savings, the payback period if you add installation cost and rebates.

Here's how to calculate heat pump savings. The calculator figures out how much heat your current system delivers. Fuel usage times energy content times system efficiency.

Then it figures out how much electricity a heat pump would need to deliver that same heat, using your rate and the COP. Heat pump electricity use equals heat delivered divided by COP. Multiply that by your electricity price. Compare the two. Not magic. Just division and multiplication.

You can try it here: It works with natural gas, oil, propane, or electric resistance. You enter your actual fuel price and electricity rate, not some national guess.

I ran my numbers. COP of three point zero, electricity at eighteen cents per kWh. The heat pump would cost more to run than my gas furnace. I stared at the result for a while. All that hype, and in my specific situation, it was a net loss. Not because heat pumps are bad. Because my gas is cheap and my electricity is not. The calculator was honest about it. Showed me a negative savings number instead of pretending.

My friend Priya, she lives outside Boston. Works in IT, knows her way around a spreadsheet. She ran her numbers through the same heat pump savings calculator. Her oil furnace was costing her a fortune. Her heat pump estimate came back with real savings. Hundreds per year, payback in under five years with rebates. She switched. She's warm, her bill dropped, and she sends me screenshots every cold month. Smugly.

That's the thing. How much money can you save with a heat pump depends entirely on where you live and what you pay. Is a heat pump cheaper than gas? Sometimes, but not always. It depends heavily on the price gap between electricity and natural gas in your area. In places with cheap gas and pricier electricity, a heat pump can cost more to run even though it's more efficient at converting energy into heat.

In regions with higher gas prices or cheaper electricity, heat pumps often come out ahead. Run your own local prices through a calculator rather than relying on a national average, since the gap between gas and electricity pricing varies enormously by location.

Is a heat pump cheaper than oil? Usually, since heating oil tends to be one of the more expensive fuels per unit of heat delivered. Most homes switching from oil to a heat pump see meaningful savings, though your exact result depends on your local oil and electricity prices.

Is a heat pump cheaper than propane? Often. Propane tends to sit between natural gas and heating oil in cost per unit of heat, and because propane is often relatively expensive, heat pumps frequently offer solid savings for propane heated homes. Is a heat pump cheaper than electric resistance heating? In almost every case, yes.

Electric resistance heat converts electricity to heat at close to one hundred percent efficiency, while a heat pump with a COP of three point zero delivers around three times as much heat per unit of electricity. Homes switching from electric resistance heat to a heat pump commonly see the largest percentage savings of any comparison.

How much electricity does a heat pump use? This depends on how much heat your home needs and the heat pump's COP. A higher COP means less electricity is needed to deliver the same amount of heat. The calculator estimates your specific annual electricity use based on your current heating usage and the efficiency values you enter.

How long does a heat pump take to pay for itself? Payback period is your net installation cost after any rebates divided by your estimated annual savings. If annual savings are small, payback can take many years. If savings are strong and rebates are available, payback can happen in just a few years. A good heat pump payback period calculator shows this figure directly once you enter your installation cost and any expected rebates.

I also wanted to see what the heat pump would do to my total electricity bill. Because even if heating gets cheaper, if it shifts from gas to electric, that electricity bill is going to look different. So I used an electricity bill calculator to model it. Added the heat pump's estimated kWh to my usual usage, kept my rate and fixed charges, and saw the new total. It helped. Context matters.

And I checked what my space heater cost per hour with an energy cost calculator. Just out of curiosity. Turns out it was atrocious. I stopped using it.

I don't know if I'll switch to a heat pump. The math says no, for now. But gas prices change. Electricity rates change. Rebates come and go. What I know is this. When a contractor tells me it'll pay for itself, I'll ask to see the calculation. And if they can't show me, I'll show them mine.

What does it really mean to have an honest tool. Maybe it means telling you what you don't want to hear.