kWh to CO2 Converter
| kWh | kg CO2 | What it is |
|---|---|---|
| 100 | 69.86 | a week of family electricity |
| 500 | 349.30 | an EV's full charge, x8 |
| 900 | 628.73 | the average US home-month |
| 3,000 | 2,095.77 | a home quarter with electric heat |
Every kilowatt-hour drawn from the average US grid carries about 699 grams of CO2 - the factor inside the EPA's greenhouse-gas equivalencies calculator, averaged across the national generation mix of gas, coal, nuclear, hydro, wind and solar. Type any electric quantity and the converter reads it in carbon: an EV charge, a month of air conditioning, a year of always-on computers.
The number is an honest average, not a personal one - a Coal-country home can emit twice this per kWh while a Hydro-country home emits a tenth - because the grid mix varies by region and by hour. But for comparing appliances to each other, sizing a solar array, or putting a number on an EV against a gasoline car, the national factor is the shared yardstick the federal calculator uses.
How to use
- Type kWh from a bill line, an appliance rating times hours, or an EV battery size, and read the CO2 in kilograms.
- Compare machines, not just totals: a 1,500 W space heater run 8 hours draws 12 kWh - about 8.4 kg of CO2, every cold day.
- For EV-vs-gas math, charge the battery here, then run the same miles through the gasoline factor: 8,887 grams per gallon.
Frequently asked questions
How much CO2 does one kilowatt-hour produce?
About 699 grams on the average US grid - the factor printed inside the EPA's equivalencies calculator (0.000699 metric tons per kWh). It is a rolling national average of every power plant's output divided by every meter's demand, so a specific home in a specific region can sit far above or below it, but federal comparisons run on this shared number.
Why does the grid factor vary so much by region?
Because the generation mix does: a hydro-heavy Pacific Northwest grid emits a fraction of the national average per kWh, while coal-leaning grids emit well above it. The same appliance, plugged in in Seattle versus St. Louis, carries a different carbon price tag - one reason 'plug-in everywhere' claims for electric machines need a map, not a single number.
How much CO2 does an EV charge add?
A 60 kWh full charge works out to about 42 kilograms of CO2 on the average grid - roughly 105 miles of average driving emissions. The EV still usually wins per mile because electric drivetrains waste far less energy than gasoline engines, but the gap is a mix question: the cleaner the grid, the wider the EV's lead grows every year without the car changing.
Do solar panels change the number?
Yes, dramatically - rooftop solar generation displaces grid electricity, so each self-supplied kWh avoids the roughly 699-gram grid factor (net of the panel's own embodied emissions, which run a small fraction of that over its life). This converter prices grid kilowatt-hours; the solar case is better described as kilowatt-hours you no longer need to convert.
Where does the exact factor come from?
The EPA's greenhouse-gas equivalencies calculator prints its electricity factor as 0.000698590164196629 metric tons of CO2 per kilowatt-hour - this converter runs the same constant, rounded for display. The agency updates it as the grid decarbonizes, so the factor inches down over the years; the older print you may see quoted elsewhere is a previous vintage.