This carbon footprint calculator estimates your household’s annual CO₂-equivalent emissions from the big three: home energy, driving and flying — using standard US emission factors, with every factor shown so the number can be argued with honestly.
Factors used: electricity 0.386 kg CO₂/kWh (US grid average — yours varies by state from ~0.1 hydro-heavy to ~0.9 coal-heavy), natural gas 5.3 kg/therm, gasoline 8.887 kg/gallon burned, flights ≈ 0.18 kg per passenger-mile (economy, typical load factors; high-altitude effects may raise the climate impact beyond CO₂ alone).
What This Counts (and What It Doesn’t)
This is a direct-energy footprint — the emissions from energy you personally burn or buy. It excludes the embodied emissions of food, goods, housing construction and services (a full consumption footprint adds those and is considerably bigger — the average US total footprint runs ~14–16 t per person all-in). Direct energy is the part with the clearest math and the most actionable levers, which is why calculators start here. The cost side of the same kilowatt-hours lives in our Electricity Cost Calculator; your car’s real economy belongs in the MPG Calculator. Part of our Ecology Calculators collection.
Worked Example (Verified)
The default household (6,000 kWh, 400 therms, 12,000 miles at 25 mpg, 5,000 flight miles):
- Electricity: 6,000 × 0.386 = 2,316 kg · Gas: 400 × 5.3 = 2,120 kg → home = 4.44 t
- Driving: 12,000 ÷ 25 = 480 gallons × 8.887 = 4.27 t
- Flights: 5,000 × 0.18 = 0.90 t
- Total ≈ 9.60 tonnes CO₂e per year for the household’s direct energy
Context That Makes the Number Useful
- Global average total footprint is ~4.7 t per person; the US averages roughly triple that all-in. A direct-energy total under ~5 t/person is already lean by US standards.
- The levers, in usual order of size: car miles & vehicle efficiency, home heating fuel, flight count, then electricity (as grids clean, the electricity slice shrinks on its own).
- One transatlantic round trip ≈ 1.5–2 t in this accounting — the reason flight miles dominate many otherwise-frugal footprints.
- EV switch on the default car (see our EV Savings Calculator) cuts driving emissions roughly 60–70% on today’s average grid, more on cleaner grids.
Related Tools
- EV Savings Calculator — the driving slice, converted
- Solar Panel Calculator — shrinking the electricity slice
- Ecology Calculators — the full collection
Frequently Asked Questions
What is a good carbon footprint?
For direct energy alone, under ~5 tonnes per person per year is comparatively low in the US. Climate targets consistent with 2°C pathways imply total footprints converging toward ~2 t/person by mid-century — the context behind every reduction conversation.
How much CO2 does driving produce per mile?
At 25 mpg: 8.887 kg per gallon ÷ 25 = ~0.36 kg per mile. At 40 mpg it’s 0.22; in a 15 mpg truck, 0.59. The calculator uses your actual mpg, because the fleet average describes nobody’s actual car.
Why do flight emissions vary between calculators?
Assumptions: aircraft type, load factor, cabin class (business seats claim ~2–3× the floor space), and whether high-altitude non-CO₂ effects (contrails, NOx) are multiplied in. This page uses 0.18 kg/passenger-mile for economy CO₂ and flags the multiplier question in its notes.
Is home electricity really that carbon-intensive?
It depends entirely on your grid: 0.386 kg/kWh is the US average. Coal-heavy grids approach 0.9; hydro/nuclear-heavy regions run near 0.05–0.15. Your utility publishes its mix — the biggest single uncertainty in this whole calculation.
What’s the fastest way to cut a household footprint?
Usually: drive less or electrify the car, weatherize and electrify heating, and scrutinize flights. This calculator’s breakdown tells you which of those is your biggest slice — personal order matters more than generic lists.
Is this carbon footprint calculator free?
Yes — free, instant, no sign-up, and no data leaves your browser.