HeatWise

Heat Pump Break-Even SCOP Calculator

The exact efficiency a heat pump needs to be cheaper than your boiler — from just four numbers.

Electricity price ($/kWh)

Current fuel price ($/kWh)

Current system efficiency (%)

Your heat pump's expected SCOP

Break-even SCOP

3.09

If your heat pump's real-world SCOP is above the break-even figure, it's cheaper to run than your current fuel at these prices. Below it, the heat pump costs more per unit of heat — usually a sign of a high electricity-to-fuel price ratio or a low SCOP.

Heat pump cost / kWh heat: $0.075
Current cost / kWh heat: $0.078
Running-cost difference: 3.6%

What you entered

Electricity price ($/kWh): 0.24Current fuel price ($/kWh): 0.07Current system efficiency (%): 90Your heat pump's expected SCOP: 3.2

1
Current cost per kWh of heat
$0.07 ÷ 90%= $0.078/kWh
2
Heat-pump cost per kWh of heat
$0.24 ÷ SCOP 3.2= $0.075/kWh
3
Break-even SCOP
$0.24 × 90% ÷ $0.07= 3.09
4
Your SCOP vs break-even
3.2 vs 3.09= cheaper to run
5
Running-cost difference per kWh heat
($0.078/kWh − $0.075/kWh) ÷ $0.078/kWh= 3.6%

Result

Break-even SCOP: 3.09

You need a SCOP of 3.09 to break even; your expected 3.2 beats that, making the heat pump about 3.6% cheaper per unit of heat at these prices.

Break-even heat pump SCOP at common electricity and gas prices

Every row assumes a 90% efficient condensing gas boiler as the system being replaced. The break-even SCOP is the electricity price times that 90% efficiency, divided by the gas price: at or above it a heat pump delivers heat more cheaply than the boiler, below it the boiler wins. The last column is the running-cost gap this calculator reports for a heat pump achieving a seasonal COP of 3.2.

Electricity ($/kWh)	Gas ($/kWh)	Break-even SCOP	Boiler heat cost ($/kWh heat)	Running-cost gap at SCOP 3.2
$0.14	$0.05	2.52	$0.056	21.2%
$0.15	$0.06	2.25	$0.067	29.7%
$0.18	$0.06	2.70	$0.067	15.6%
$0.20	$0.07	2.57	$0.078	19.6%
$0.24	$0.07	3.09	$0.078	3.6%
$0.28	$0.08	3.15	$0.089	1.6%
$0.35	$0.10	3.15	$0.111	1.6%
$0.32	$0.08	3.60	$0.089	-12.5%
$0.40	$0.10	3.60	$0.111	-12.5%

A positive running-cost gap means the heat pump is that much cheaper per kWh of delivered heat; a negative figure means it costs that much more. Notice that the break-even SCOP depends only on the ratio between the two prices, not their absolute level: $0.35 electricity against $0.10 gas gives the same 3.15 target as $0.28 against $0.08. Replacing a less efficient system lowers the bar - oil at $0.11/kWh through an 85% boiler with $0.24 electricity breaks even at a SCOP of just 1.85. Real-world SCOP typically lands between 3.0 and 4.0 and falls as flow temperature rises, so use a surveyed figure for your own emitters rather than the datasheet best case. These are running-cost comparisons only: they exclude installation cost, grants, standing charges, and any heat-loss or comfort differences. Illustrative - run your own numbers with your actual tariff and a professional heat-loss survey before committing.

A heat pump break-even calculator answers the sharpest version of the electrification question: exactly how efficient does a heat pump have to be to cost less to run than my current heating? Instead of estimating a full annual bill, it isolates the single number that decides the outcome — the break-even seasonal COP (SCOP) — so you can compare it against what a heat pump will realistically achieve in your home. If your expected SCOP clears the break-even figure, the heat pump is cheaper per unit of heat; if it falls short, it is not, and you know immediately by how much.

The logic rests on comparing the cost of a kilowatt-hour of delivered heat from each system. Your current system's heat costs its fuel price divided by its efficiency: a gas boiler that is 90% efficient burning gas at seven cents per kWh delivers heat at about 7.8 cents per kWh. A heat pump's heat costs its electricity price divided by its SCOP: at 24 cents per kWh electricity and a SCOP of 3.2, that is 7.5 cents per kWh of heat. Setting those two equal and solving gives the break-even SCOP directly — electricity price multiplied by your current efficiency, divided by your fuel price. Any SCOP above that line means cheaper heat; anything below means dearer heat. The calculator shows both per-kWh heat costs, the break-even SCOP, and where your expected SCOP sits relative to it, along with the resulting percentage difference in running cost.

This break-even framing is powerful because it cuts through the noise of annual estimates and exposes the real driver: the ratio between your electricity price and your fuel price. Where electricity is cheap relative to gas, the break-even SCOP is low and almost any heat pump wins; where electricity is expensive relative to gas, the break-even SCOP climbs and only a well-designed, low-flow-temperature system will beat the boiler. It also makes the levers obvious — a dedicated heat-pump electricity tariff lowers the electricity price and drops the break-even line, while larger radiators or underfloor heating raise the achievable SCOP. Use this as the quick screening test before committing to a full running-cost or payback analysis: if your realistic SCOP comfortably clears the break-even point, the economics are on your side; if it does not, focus on the tariff and system design before anything else. It compares running cost only and is not a substitute for a professional heat-loss survey.

The price ratio sets the target

Break-even SCOP is electricity price × current efficiency ÷ fuel price. That means it's really about the ratio between what you pay for electricity and for fuel. If electricity costs 3× your gas price, you need a SCOP above roughly 2.7 (for a 90% boiler) just to break even; a special EV/heat-pump tariff that narrows the ratio can drop the target dramatically.

How to clear the break-even line

Two levers raise a real-world SCOP above the break-even point: a cheaper electricity tariff (lowers the target) and a lower flow temperature (raises the achievable SCOP). Larger radiators, underfloor heating, and good insulation all let a heat pump run cooler and more efficiently. If your SCOP is below break-even, fix the tariff and the flow temperature before assuming a heat pump can't work.

Frequently asked questions

My electricity is $0.24/kWh, gas is $0.07/kWh, and my boiler is 90% efficient — what SCOP do I need?

The break-even SCOP is 0.24 × 0.90 ÷ 0.07 ≈ 3.09. A heat pump achieving a real-world SCOP above about 3.1 will be cheaper to run than your gas boiler at these prices; below that it costs more per unit of heat.

What is SCOP and how does it differ from COP?

COP is a heat pump's efficiency at a single operating point; SCOP (Seasonal COP) is the average across a whole heating season, including cold spells. Always break-even against SCOP, not the best-case COP on the datasheet — real-world SCOP is typically 3.0-4.0 and drops at high flow temperatures.

Why does my current boiler's efficiency matter?

Because it sets how much useful heat your fuel actually delivers. A 90% boiler wastes 10% up the flue, so your real cost per unit of heat is higher than the raw gas price. A less efficient system makes the heat pump's break-even SCOP lower (easier to beat); a very efficient condensing boiler raises the bar.

How is this different from the heat pump running cost calculator?

The running cost calculator turns your actual annual fuel bill into a full yearly cost and saving. This one isolates the single break-even SCOP threshold, so you can instantly judge whether a given heat pump will be cheaper before running the full numbers. Use this to screen, then that to size the annual saving.