Frequently asked questions
Short, plain answers. If you do not see your question, open an issue on GitHub.
Is my data sent anywhere?
No. Everything runs in your browser. There is no backend. The site is static HTML, CSS, and JavaScript served from a CDN. No analytics, no tracking pixels, no cookies you did not opt into.
Why does my country average differ from what I see elsewhere?
We use territorial (production-based) emissions for 2022 from Our World in Data. Some calculators use consumption-based emissions, which add the carbon embedded in imports. Net importers like the UK and Switzerland look bigger under consumption-based; big exporters like China look smaller.
Production-based numbers are the comparable apples-to-apples baseline used by the IPCC and UNFCCC.
Why is my electric car not zero?
Because the electricity to charge it is not zero. We multiply the EV's per-km kWh by your country's grid carbon intensity. France (56 g/kWh) makes EVs nearly carbon-free; Poland (660 g/kWh) makes the same EV emit about as much as a small efficient petrol car.
Why is the flight number so high?
Two reasons. First, you are likely flying further than you remember; one return long-haul is 18,000 km of cabin time. Second, planes emit at altitude and that has a non-CO2 warming effect (contrails, NOx). DEFRA applies a 1.9x multiplier to ground-level CO2; we follow that.
If you only count CO2, divide the flight number by 1.9.
How accurate is the number?
Plus or minus 25-40 percent on the total. Diet and home heating are the most reliable categories. Stuff (consumption) is the most uncertain because it is so behaviour-dependent.
Use the number to compare lifestyle changes against each other, not as a forensic audit.
What does the percentile mean?
It tells you where your number falls in your country's distribution of personal footprints. Top 10% in the US has a much bigger absolute footprint than top 10% in Brazil; the percentile is country-relative.
Should I add offsets?
No. We deliberately do not subtract offsets. The science on most voluntary offset programmes is contested, and even the good ones do not erase tonnes from your gross emissions; they fund avoidance or removal elsewhere.
If you buy offsets, count them as a separate climate action, not as cancellation.
Is going vegan really the biggest move?
For diet, yes (meat-heavy to vegan saves about 2.3 tCO2/yr). But for an average European, a single skipped long-haul flight saves about as much as a full year vegan. Insulating a leaky house and switching to a heat pump is bigger than either.
The biggest leverage usually lives in housing and air travel, not the dinner plate.
Why is consumption only three buckets?
Because line-item consumption emissions are very noisy. A more granular form would imply a precision we do not have. Three buckets is honest about the resolution of the data.
How can I help?
Open issues for data fixes or features. Star the GitHub repo. If the tool is useful, a small Ko-fi tip lets me build more open educational tools.