Climate & Environment
Carbon Footprint Calculator
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How to use it
Using the carbon footprint calculator
- 01
Enter energy use
Copy annual totals from your utility bills for electricity (kWh) and natural gas (therms). Twelve monthly bills beat one month multiplied by twelve if usage is seasonal.
- 02
Add travel
Estimate yearly car mileage from odometer readings or commute math, then count your round-trip flights by haul length.
- 03
Compare and target
The breakdown shows which line dominates. The cheapest cuts usually come from the largest row first; often heating or driving.
Good to know
What counts as “household” here
This estimate covers the three biggest controllable categories: home energy, personal driving and air travel. Food, purchases and public services add more on top, so full lifestyle footprints run higher than these numbers alone.
Why factors are averages
Grid carbon intensity varies enormously; hydro-heavy regions emit a fraction of coal-heavy ones, and the mix shifts hourly. Using a single national approximation keeps this tool simple; for precision, substitute your utility’s published emission rate.
Where reductions pay off most
In most US households, driving and home heating dominate. Swapping one long-haul flight saves roughly as much as a year of careful thermostat management, while an efficient vehicle or heat-pump conversion compounds over many years.
How it's calculated
The math behind this calculator
CO₂e = kWh×0.4 + therms×5.3 + miles×0.40 (kg) + flights×0.3/1.0 (tonnes)Each activity is multiplied by a published average emission factor and summed. Electricity uses an approximate US grid average of 0.4 kg CO₂e per kWh; natural gas contributes about 5.3 kg per therm burned; driving assumes a typical petrol car at 0.40 kg per mile.
Flights are counted as whole round trips: roughly 0.3 tonnes CO₂e each for short-haul and 1.0 tonne for long-haul. The result is compared with the commonly cited ~16-tonne US household average to give context.
Assumptions & limitations
- Electricity grid factor fixed at 0.4 kg CO₂e/kWh; an approximate US average; your regional grid may differ substantially.
- Natural gas at 5.3 kg CO₂e per therm.
- Driving at 0.40 kg CO₂e/mile for an average petrol car; electric or hybrid vehicles will be lower.
- Flights estimated at 0.3 tonnes CO₂e per short-haul and 1.0 tonne per long-haul round trip, excluding radiative-forcing multipliers.
- Other household sources (food, goods, waste) are not included; treat the total as transport-and-energy only.
Worked example
A household using 9,000 kWh of electricity, 600 therms of gas, driving 12,000 miles and taking two short-haul plus one long-haul round trip lands near 13.18 tonnes of CO₂e a year; under the rough 16-tonne US average.
FAQ
Frequently asked questions
- Is 16 tonnes really the US average?
- It is a commonly cited planning figure for per-household energy and transport emissions; national inventories report per-capita figures near 14–16 tonnes when all sectors are included. Treat it as orientation, not gospel.
- Does the electricity factor match my region?
- Probably not exactly. 0.4 kg/kWh approximates the US average; grids in the Pacific Northwest can be below 0.1 while some Midwest grids exceed 0.7. Check your utility’s disclosure for a local number.
- Why are flights counted per round trip?
- Frequent travellers think in trips, not kilometres. A short-haul round trip (under ~3,700 km each way) emits around 0.3 tonnes per passenger in economy; long-haul is closer to 1.0 tonne.
- Are offsets included?
- No; this measures gross emissions. If you buy offsets, use the flight-emissions calculator’s indicative offset cost row as a rough budgeting reference.
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