Energy Usage & Carbon Impact
Calculate carbon footprint from electricity, gas, driving, and flights. Enter values for instant results with step-by-step formulas.
Formula
Total CO2 = (kWh × Grid Factor) + (Therms × 11.7) + (Miles/MPG × 19.6) + (Flight Hours × 53)
Each energy source has a CO2 emission factor. Electricity varies by grid mix. Natural gas is 11.7 lbs CO2/therm. Gasoline is 19.6 lbs CO2/gallon. Flights average 53 lbs CO2/hour.
Worked Examples
Example 1: Average US Household
Problem:Monthly: 900 kWh electricity (US avg grid), 50 therms gas, 1,000 vehicle miles (25 MPG), 2 flight hours.
Solution:Electricity: 900 × 0.92 = 828 lbs CO2\nNatural Gas: 50 × 11.7 = 585 lbs CO2\nVehicle: (1000/25) × 19.6 = 784 lbs CO2\nFlights: 2 × 53 = 106 lbs CO2\n\nTotal: 2,303 lbs = 1.15 tons/month\nAnnual: 13.8 tons\n\nUS Average: 16 tons/year\nThis household: 86% of average\n\nTop reduction opportunity:\nSwitch to 50% renewable electricity\nSaves: 414 lbs/month = 2.5 tons/year
Result:1.15 tons/month | 13.8 tons/year | 86% of US avg | Electricity is largest source
Example 2: Eco-Conscious Urban Dweller
Problem:Monthly: 400 kWh (California grid), 20 therms gas, 200 miles (hybrid 45 MPG), 0 flights, 50% renewable.
Solution:Electricity: 400 × 0.52 × 0.5 = 104 lbs CO2\nNatural Gas: 20 × 11.7 = 234 lbs CO2\nVehicle: (200/45) × 19.6 = 87 lbs CO2\nFlights: 0 lbs CO2\n\nTotal: 425 lbs = 0.21 tons/month\nAnnual: 2.5 tons\n\nUS Average: 16 tons/year\nThis person: 16% of average (Excellent!)\n\nAlready low-carbon lifestyle.\nFurther reduction: heat pump (replace gas), EV.
Result:0.21 tons/month | 2.5 tons/year | 16% of US avg | Near carbon-neutral
Example 3: Frequent Flyer
Problem:Monthly: 600 kWh (clean grid), 30 therms, 500 miles (30 MPG), 20 flight hours (business travel).
Solution:Electricity: 600 × 0.30 = 180 lbs CO2\nNatural Gas: 30 × 11.7 = 351 lbs CO2\nVehicle: (500/30) × 19.6 = 327 lbs CO2\nFlights: 20 × 53 = 1,060 lbs CO2\n\nTotal: 1,918 lbs = 0.96 tons/month\nAnnual: 11.5 tons\n\nFlights = 55% of total!\n\nOne transatlantic flight ≈ 2,000 lbs CO2\n\nRecommendation:\n- Reduce flights 50% via video calls\n- Offset remaining flights: $288/year\n- Consider train for short trips
Result:0.96 tons/month | Flights dominate (55%) | Video calls can cut 5 tons/year
Frequently Asked Questions
What is a carbon footprint?
Carbon footprint is total greenhouse gas emissions caused by an individual, event, product, or organization, expressed as CO2 equivalent. Average American: 16 tons CO2/year. Global average: 4 tons. Target for climate goals: 2 tons/person.
How is electricity carbon calculated?
Multiply kWh used by grid emission factor (lbs CO2/kWh). Factors vary by region based on power source mix. Coal-heavy grids: 1.0-1.2 lbs/kWh. Renewables-heavy: 0.3-0.5 lbs/kWh. Your utility may publish specific factors.
What produces the most carbon at home?
Typically: heating/cooling (40-50%), water heating (15-20%), appliances (15%), lighting (10%), other (10%). Transportation often exceeds home energy. Flights are extremely carbon-intensive per hour.
Are carbon offsets effective?
Quality varies widely. Best offsets: verified (Gold Standard, Verra), additional (wouldn't happen without funding), permanent (forests can burn). Avoid cheap, unverified offsets. Reduction is always better than offsetting.