Carbon Footprint Calculator
Find out how many tonnes of CO₂ you emit each year — and which changes will have the biggest impact. Takes about 2 minutes. All data stays in your browser.
Calculate Your Carbon Footprint
Free, private, and instant — all calculations happen in your browser. We never store your data.
Transport
How the calculator works
Transport
We calculate emissions from your car type and weekly mileage, plus any flights using standard aviation emission factors from DEFRA and the IPCC.
Home energy
Heating and electricity emissions are calculated from your actual usage (kWh) multiplied by UK grid carbon intensity factors, updated for 2025.
Diet
Diet emissions are estimated from peer-reviewed lifecycle analysis studies, covering the full food supply chain from farm to plate.
Emission factors sourced from DEFRA, IEA, and the Global Carbon Project. See our methodology page for details.
Frequently asked questions
How accurate is the CarbonBuddy carbon footprint calculator?
Our calculator uses UK government DEFRA emission factors and IEA data. Results are estimates within ±10–15% of professionally calculated footprints. The calculator covers your three biggest emission sources: transport, home energy, and diet.
Is my data stored or shared?
No data is stored or shared. All calculations run entirely in your browser using JavaScript. Nothing is sent to any server. We never see your inputs or results.
What is the average UK carbon footprint?
The average UK resident emits approximately 5.5 tonnes of CO₂ equivalent per year from direct activities (transport, home energy, diet). Including consumption emissions from imported goods, the figure rises to around 10–12 tonnes.
What does CO₂e mean?
CO₂e stands for CO₂ equivalent — a standard unit that converts all greenhouse gases (CO₂, methane, nitrous oxide, etc.) into an equivalent amount of CO₂ by their global warming potential. This allows different gases to be compared on a single scale.