Carbon Footprint Calculator
Estimate annual CO₂e from electricity, gas, driving, flights, food, and waste using EPA/DEFRA factors.
Written by Golam Rabbani, Founder & Lead Engineer
How to use this carbon footprint calculator
- Enter your typical activity levels — monthly kWh and therms, weekly miles driven, annual flight miles, and kg/week of beef, poultry, dairy, and waste.
- Leave any row blank or at zero to skip it.
- Optional: click "Show / override emission factors" to swap the defaults for your local grid or DEFRA values.
- Press Calculate to see your total annual CO₂e, per-category breakdown, and your share of the US per-capita household average.
About this carbon footprint calculator
The carbon footprint calculator converts each of your typical activities into kilograms of CO₂-equivalent per year using emission factors published by the US EPA (Greenhouse Gas Equivalencies, 2024), US EIA (Carbon Dioxide Emissions Coefficients, 2023), UK DEFRA (2024 conversion factors), and Poore & Nemecek (Science 360:987, 2018). Each input is normalized to an annual basis (×12 for monthly, ×52 for weekly), multiplied by its kg CO₂e per unit, and summed.
Example: 900 kWh/month electricity, 50 therms/month gas, 200 miles/week driving, 0.5 kg/week of beef. Electricity: 900 × 12 × 0.386 = 4,169 kg. Gas: 50 × 12 × 5.30 = 3,180 kg. Driving: 200 × 52 × 0.400 = 4,160 kg. Beef: 0.5 × 52 × 27.0 = 702 kg. Total = 12,211 kg ≈ 12.2 tonnes CO₂e/year, which is 163% of the EPA-reported US per-capita household average of 7.5 t.
Default factors are global averages; your real footprint depends on your local grid mix, vehicle fuel economy, and supply chains. Override each factor with your utility's number for accuracy. Note: this tool counts CO₂e — methane and N₂O converted to CO₂-equivalent using GWP100.
FAQ
- What is "CO₂e"?
- CO₂-equivalent: methane, nitrous oxide, and other greenhouse gases converted to the warming impact of an equivalent mass of CO₂ over 100 years (GWP100). One kg of methane = 25 kg CO₂e under IPCC AR5.
- Why is beef's factor so high?
- Beef's 27 kg CO₂e/kg comes from Poore & Nemecek's 2018 meta-analysis — it combines feed production, methane from cattle digestion, manure management, and land-use change. Plant proteins typically run 1–3 kg CO₂e/kg.
- How does my local electricity grid affect the result?
- A lot. The default 0.386 kg CO₂e/kWh is the US national average. France (mostly nuclear) is ~0.05; coal-heavy regions are 0.8+. Get your utility's "Power Content Label" or look up your eGRID subregion to override the factor.
- Does this include manufacturing of goods I buy?
- No — scope 3 "purchased goods" emissions aren't directly modeled. They typically add 25–35% to a household total. For a fuller picture, use UK Carbon Trust or CoolClimate tools.
- Where does the 7.5 tonnes per-capita benchmark come from?
- It's the EPA-reported US per-capita residential carbon footprint (electricity + gas + heating + transportation for a typical household member). Global average is ~4.7 t; the IPCC 1.5°C-aligned target is ~2 t per person by 2030.