Plug-in Hybrid Economy Calculator
See how much a plug-in hybrid saves in cost and CO2 against a conventional car, based on how much of your driving runs on electric power.
🔌 What is a Plug-in Hybrid Economy Calculation?
A plug-in hybrid economy calculation compares the annual fuel cost and CO2 emissions of a plug-in hybrid electric vehicle, PHEV, against a conventional gas-only car, taking into account how much of the PHEV's driving actually happens on electric power. A PHEV is not simply an electric car or simply a hybrid; it is both, switching between a battery pack charged from the grid and a gas engine once the battery is depleted, so its real-world economy depends heavily on driving habits rather than the vehicle alone.
Shoppers use this calculation to decide whether a PHEV makes financial sense for their specific commute pattern, fleet managers use it to estimate fuel budgets across vehicles with different charging habits, and sustainability teams use it to estimate the CO2 reduction a PHEV fleet delivers against a conventional baseline, which depends on local grid carbon intensity as much as on the car itself.
The number that changes the outcome more than any other is the share of driving actually done on electric power. A PHEV plugged in every night and used mostly for short trips under its electric range can run 70 to 90 percent electric, capturing most of the available savings, while the same car rarely plugged in behaves closer to a conventional hybrid and captures far less benefit.
This calculator focuses on running costs and operating emissions only. It does not include the PHEV's typically higher purchase price, available tax incentives, insurance or maintenance differences, all of which matter for a full cost-of-ownership decision but sit outside the scope of a fuel and electricity comparison.
📐 Formula
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 — A Typical Commuter With a Home Charger
15,000 km/yr, 60% electric, 18 kWh/100km at $0.15/kWh, 6 L/100km PHEV gas at $1.50/L, 7 L/100km conventional car
Example 2 — A High-Mileage Driver, Mostly Electric
20,000 km/yr, 80% electric, 17 kWh/100km at $0.12/kWh, 5.5 L/100km PHEV gas at $1.30/L, 7.5 L/100km conventional car
Example 3 — A Driver Who Rarely Plugs In
10,000 km/yr, 30% electric, 19 kWh/100km at $0.20/kWh, 6.5 L/100km PHEV gas at $1.70/L, 6.5 L/100km conventional car
❓ Frequently Asked Questions
🔗 Related Calculators
How much can a plug-in hybrid save compared to a conventional car?
At 15,000 km a year with 60 percent driven on electric, an 18 kWh/100km PHEV at $0.15/kWh electricity and $1.50/L gas costs about $783 a year, against $1,575 for a conventional car at 7 L/100km, a saving of about $792 a year.
How much CO2 does a plug-in hybrid save?
Using the same example, a PHEV's combined electric and gas emissions come to about 1,561 kg CO2e a year against 2,426 kg for a conventional car, a reduction of roughly 865 kg a year, assuming a grid intensity of 0.45 kg CO2 per kWh.
What percent of driving needs to be electric to make a PHEV worthwhile?
There is no fixed threshold, since even a modest electric share still saves some fuel and CO2 compared with a conventional car. The savings scale roughly linearly with electric share, so a PHEV charged only occasionally captures proportionally less of the potential benefit.
How is the electric cost calculated?
Electric kilometres divided by 100, multiplied by the battery consumption in kWh per 100 km, multiplied by the electricity price per kWh. At 9,000 electric km, 18 kWh/100km and $0.15/kWh, that is 90 times 18 times 0.15, which is $243 a year.
Does a PHEV's gas engine use more fuel than a regular hybrid's?
Often somewhat more per litre-equivalent, because the PHEV carries a heavier battery pack and drivetrain that the gas engine has to move once the battery is depleted, which is why this calculator lets you set the gas-mode consumption separately from a conventional car's.
What grid CO2 factor should I use?
Use your local grid's average carbon intensity if you know it; otherwise 0.4 to 0.5 kg CO2 per kWh is a reasonable placeholder for a mixed fossil and renewable grid. Regions with more hydro, nuclear or wind power should use a lower figure.
Does this calculator include the cost of buying the car?
No, it only compares fuel and electricity running costs. Purchase price, incentives, resale value and maintenance are not included, and any of those can shift the total cost of ownership comparison in either direction.
How does the chart help pick a target charging habit?
It shows how the PHEV's annual cost changes as the electric-driving share moves from 0 to 100 percent, with your current setting marked, so you can see roughly how much cheaper the car becomes if you commit to charging more consistently.
Is a PHEV always better for CO2 than a conventional car?
Almost always, because even its gas-mode driving typically consumes similar fuel to a comparable conventional car, and any electric-mode driving adds a further reduction. The exception is a grid with very high carbon intensity combined with a very low electric-driving share.
What is a realistic electric range and consumption for a PHEV?
Most PHEVs on the market have all-electric ranges between 20 and 80 km and battery consumption in the range of 15 to 22 kWh per 100 km, broadly similar to a compact full battery-electric vehicle.
How does annual mileage affect the comparison?
Every cost and CO2 figure in this calculator scales directly with annual mileage, so doubling the distance driven doubles both the PHEV's and the conventional car's totals, leaving the percentage savings roughly unchanged.
Why does the calculator separate gas price used for both cars?
Because the PHEV and the conventional comparison car are assumed to buy fuel at the same local price, isolating the comparison to consumption efficiency and electric-driving share rather than any difference in fuel pricing.