Carbon Footprint Calculator
Estimate your annual emissions across travel, home energy and diet, measured in tonnes of CO2 equivalent. The value is less in the total than in seeing which categories dominate.
Formula
Annual CO₂e = Σ (activity amount × its emission factor)
- Electricity about 0.5 kg per kWh
- Car travel about 0.411 kg per mile
- A long-haul return flight about 90 kg per hour in the air
300 kWh a month: 300 × 0.5 × 12 = 1,800 kg of CO₂e a year
Where Emissions Come From
For a typical UK household, the largest contributors are:
- Home heating, usually the single biggest item for gas-heated homes
- Car travel, at roughly 120–170 g CO2 per km for a petrol car
- Flights, which are extremely concentrated: a single long-haul return can exceed a tonne per passenger
- Diet, where red meat and dairy dominate food emissions
The UK average is around 5 to 7 tonnes CO2e per person annually, against a global average near 4.5.
A Few Choices Dominate
Footprints are highly skewed. Flying, driving and home heating typically account for most of an individual total, which means a small number of decisions carry most of the weight.
Reducing one long-haul flight a year usually outweighs a great deal of careful recycling. That is not an argument against small habits, but it is worth knowing where the leverage actually is before optimising the wrong thing.
Treat the Number Loosely
Any footprint figure is an estimate built on averages, and different calculators use different boundaries — some count only direct emissions, others include the embedded carbon of goods you buy.
That means totals from two calculators are rarely comparable. Use one consistently to track change over time rather than treating any single figure as precise, and expect the underlying emission factors to shift as grids decarbonise.
Quick Reference
| Activity | Amount | Annual CO₂e |
|---|---|---|
| Electricity | 200 kWh a month | 1,200 kg |
| Electricity | 300 kWh a month | 1,800 kg |
| Driving | 50 miles a week | 1,069 kg |
| Driving | 100 miles a week | 2,137 kg |
| Driving | 200 miles a week | 4,274 kg |
Frequently Asked Questions
- What is the average carbon footprint in the UK?
- Around 5 to 7 tonnes of CO2 equivalent per person a year, against a global average nearer 4.5 tonnes.
- What has the biggest impact?
- Flying, car travel and home heating dominate most individual footprints. A single long-haul return flight can exceed a tonne per passenger.
- Why do different calculators give different answers?
- They use different boundaries and emission factors. Some count direct emissions only, others include the embedded carbon of purchases.
- Does recycling make much difference?
- Less than travel and heating choices. It is worth doing, but the leverage sits overwhelmingly in flights, driving and how you heat your home.