Carbon Footprint Formula
Estimate CO2 emissions from energy use, travel, and consumption.
Calculate your environmental impact in tonnes of CO2.
The Formula
CO₂ = Activity Data × Emission Factor
A carbon footprint is the total greenhouse gas emissions from an activity, expressed in CO₂ equivalents. Each type of activity (driving, electricity use, flying) has a specific emission factor.
Variables
| Symbol | Meaning |
|---|---|
| CO₂ | Carbon dioxide emissions (kg or tonnes) |
| Activity Data | Amount of the activity (km driven, kWh used, etc.) |
| Emission Factor | CO₂ produced per unit of activity (kg CO₂ per unit) |
Example 1
Calculate CO₂ from driving 15,000 km per year in a gasoline car
Average emission factor for gasoline car: 0.21 kg CO₂/km
CO₂ = 15,000 × 0.21
CO₂ = 3,150 kg = 3.15 tonnes per year
Example 2
Calculate CO₂ from using 5,000 kWh of electricity per year (US average grid)
US average emission factor: 0.42 kg CO₂/kWh
CO₂ = 5,000 × 0.42
CO₂ = 2,100 kg = 2.1 tonnes per year
When to Use It
Use the carbon footprint formula when:
- Estimating personal or household greenhouse gas emissions
- Comparing the environmental impact of different activities
- Setting goals for reducing carbon emissions
- Reporting corporate sustainability metrics