Carbon Footprint Calculator
Estimate your annual CO₂e from home energy, driving, flights and diet, see which part dominates, and compare the total against national averages.
How to use it
- Fill in the figures from your energy bills — they show annual kWh.
- Home energy is divided between the people in your household; travel and food are not.
- The breakdown bar is the useful part: it shows which single change would matter most.
Examples
| 3000 kWh, 11000 kWh gas, 900 L petrol, 2 people | about 5.5 t CO₂e |
| One long-haul return flight | adds 1.8 t on its own |
A carbon footprint totals the greenhouse gas emissions a person is responsible for over a year, expressed as CO₂e — carbon dioxide equivalent, a single unit that lets emissions of methane, nitrous oxide and other gases be added to CO₂ on the same scale. This calculator builds that total from four sources: home energy, driving, flights and diet, each converted using published mid-range emission factors.
The point of the breakdown bar is not the final number so much as which category dominates it — for most people it is flights or driving, and knowing which one lets you target the change that actually moves the total.
Home energy
Electricity and gas usage, taken straight off a bill in annual kWh, are converted using grid emission factors that vary by country and by year as the generation mix shifts toward renewables. Because a household is shared, this calculator splits the home-energy portion across the number of people living there — travel and food are not split, since those are individual choices rather than shared infrastructure.
Why flights weigh so heavily
A single long-haul return flight can add more CO₂e than a year of a typical household's electricity use, and it is not a calculation quirk — burning jet fuel at altitude is simply carbon-intensive per hour of travel, and there is no efficient alternative fuel deployed at scale yet. Radiative forcing effects (the extra warming impact of emissions released at altitude) push the real climate impact higher still, though most consumer calculators, including this one, quote the CO₂ figure without that multiplier for comparability with other published tools.
Typical annual footprints for comparison
| Region | Rough average per person |
|---|---|
| United States | ~14–16 t CO₂e |
| European Union | ~6–8 t CO₂e |
| United Kingdom | ~5–6 t CO₂e |
| Global average | ~4–5 t CO₂e |
| Paris Agreement target (2050) | ~2 t CO₂e |
Reading the result honestly
Treat the absolute figure as an estimate, not an audit — emission factors vary by country, by grid mix and by year, and a personal calculator cannot capture every nuance of what you actually bought and ate. What it is genuinely good for is comparing your own choices against each other: swapping one flight for a train, or insulating a loft, and seeing which change actually shifts the total by more.
Questions people ask
How accurate is this?
It uses mid-range published emission factors, so it is good for comparing your own options against each other. Treat the absolute number as an estimate — real factors vary by country, grid and year.
Why is my flight figure so large?
Because flying is genuinely carbon-intensive per hour. A single long-haul return can exceed a year of home electricity for many households.
What is CO₂e?
Carbon dioxide equivalent. It converts other greenhouse gases such as methane into the amount of CO₂ that would cause the same warming, so everything can be added together.
Does this page work offline?
Yes, after the first visit. The service worker caches it, so the guide stays available with no connection.
Last updated 22 August 2026