EV vs Gas Emissions Calculator
An electric vehicle has no tailpipe emissions, but it is not emission-free: the electricity it uses carries the carbon intensity of your local grid. A gasoline car emits CO2 directly when fuel is burned. To compare them fairly you need annual mileage, the gas car's fuel economy, the EV's energy use per mile, the CO2 per gallon of gasoline and your grid emission factor. This calculator computes the yearly CO2 of each vehicle and the difference, with every emission factor left as an editable input so you can match your region's official figures.
EV vs gas emissions formula
Gas CO2 = (miles / mpg) * CO2 per gallon
EV CO2 = miles * kWh per mile * grid factor
CO2 saved = gas CO2 - EV CO2
Reduction % = (CO2 saved / gas CO2) * 100
A positive saving means the EV emits less over the year. A negative saving (on a very carbon-intensive grid with an efficient gas car) means the gas car emits less in operation. This compares use-phase emissions only.
What drives the comparison
- Grid carbon intensity is the single biggest lever: a clean grid makes the EV far cleaner.
- Gas fuel economy and EV efficiency vary widely by model and driving style.
- Well-to-wheel factors (including fuel and electricity production) give a fuller picture than direct combustion alone.
- Manufacturing emissions are excluded here and matter for a full lifecycle view.
EV vs gas emissions: frequently asked questions
How do EV and gas car emissions compare?
A gasoline car emits CO2 directly when fuel is burned: gallons used times the CO2 per gallon. An electric vehicle emits no tailpipe CO2 but is responsible for the emissions of the electricity it consumes: kilowatt-hours used times the grid emission factor. This calculator works out both so you can compare them on equal terms using your own driving figures.
What grid emission factor should I use?
The grid emission factor (kg CO2 per kWh) depends heavily on your local electricity mix. The US EPA publishes regional emission rates through eGRID, and national energy agencies publish equivalent figures. A grid dominated by renewables and nuclear has a low factor; a coal-heavy grid has a high one. It is a user-editable input here so you can enter the figure for your region.
How much CO2 does a gallon of gasoline produce?
The US EPA states that burning one gallon of gasoline produces about 8.89 kg of CO2. This figure is a user-editable input so you can substitute the exact value, or a well-to-wheel figure that includes fuel production emissions, from your chosen authority.
Does this include manufacturing emissions?
No. This calculator compares operating (use-phase) emissions only: the CO2 from driving each vehicle over a year. Battery and vehicle manufacturing emissions are not included, and they can be material in a full lifecycle comparison.
Official sources
- U.S. Environmental Protection Agency: Greenhouse Gas Equivalencies: calculations and references.
- U.S. Environmental Protection Agency: eGRID emission factors.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.