Why State-Level Electricity Factors Matter
The US electricity grid is not uniform. Wyoming and West Virginia generate over 80% of electricity from coal, with grid emission factors near 0.789 kg CO₂/kWh. Vermont and Washington get most power from hydro and nuclear, with factors as low as 0.010–0.090 kg/kWh. For a household using 900 kWh/month, this difference means 10.2 tons CO₂e/yr (WY) vs 0.13 tons (VT) — just from electricity. Using the US average significantly misrepresents both situations.
EVs, the Grid, and Your State
Electric vehicles are often called zero-emission, but they shift emissions from the tailpipe to the power plant. In a coal-heavy state, an EV's lifetime emissions may only be 20–30% lower than a fuel-efficient gasoline car. In a clean-grid state, the advantage grows to 70–90%. Pairing an EV with rooftop solar or a green electricity tariff can reduce transport emissions to near zero. Use the EV toggle and renewable slider together to model your scenario.
Aviation's Outsized Impact
A single business-class transatlantic round-trip emits roughly 6 tons of CO₂e per person — exceeding three months of the average American's total footprint. The seat-class multiplier accounts for the fact that business and first-class seats occupy 2.9× and 4.0× the floor space of economy seats, allocated proportionally to fuel burn. For frequent flyers, eliminating or replacing one long business-class flight with economy saves more CO₂ than a year of diet changes.
The Goods & Services Gap
Most carbon calculators omit goods and services — the embedded emissions in everything you buy. A new smartphone emits ~70 kg CO₂e in manufacturing. A pair of jeans is 33 kg. Annual household shopping of $300/month can add 6+ tons to your supply-chain footprint (Scope 3 emissions). This calculator includes a spending-based estimate using DEFRA 2022 household consumption emission factors. While less precise than activity-based accounting, it gives a meaningful order-of-magnitude for what you spend.
High-Impact Actions That Actually Work
Research by Wynes and Nicholas (2017) identified the four highest-impact personal climate actions: eliminating flights (saves 1.5–11t depending on class), going car-free or switching to an EV (saves 2–4t), eating plant-based (saves 0.8–1.5t), and switching to renewable electricity (saves 1–3t depending on state). The Reduce & Act tab ranks these actions using your specific numbers so you can prioritize the changes with the biggest return for your situation.