Methodology and factor register

How a result is calculated

Each line is annual activity × emission factor. Activity you enter (kWh, therms, gallons, miles, tons) is converted to the factor’s unit and to a yearly amount. Factors that publish carbon dioxide, methane and nitrous oxide separately are combined into CO₂-equivalent using IPCC AR5 100-year global warming potentials (CH₄ = 28, N₂O = 265), as in the EPA GHG Emission Factors Hub 2025. EPA waste factors are published on an AR4 basis and are used as published; this is disclosed on every result. Results are shown to three significant figures to avoid false precision.

Principles

• Unknown is not zero. Every input distinguishes “I know the amount”, “I don’t know” and “doesn’t apply”. Unknown amounts are left out and listed as not included, except where a documented average is offered and labeled as a default.
• No double counting. Each vehicle uses either fuel or distance; electric-vehicle charging can be marked as already in the home bill; market-based Scope 2 is never added to the location-based total.
• No offsets. Offsets, removals and certificates of neutrality are not subtracted. Renewable-energy certificates affect only the market-based Scope 2 figure, and only when the user confirms they meet the GHG Protocol Scope 2 Quality Criteria.
• Private. Calculations run in the browser. No entered data is transmitted, stored or analyzed.

Individual and household calculator

Covers home electricity (by eGRID subregion in the U.S., national grid in Brazil), natural gas, propane, heating oil, personal vehicles (fuel-based, or distance with fuel economy, or U.S. average per-mile factors), motorcycles, bus and rail, flights (short <300 mi, medium 300–2,300 mi, long ≥2,300 mi one way) and household waste. For U.S. users who don’t know their home energy use, U.S. averages from the EIA Residential Energy Consumption Survey 2020 can be applied: 881 kWh, 4,717 cubic feet of natural gas, 42 gallons of heating oil or 32 gallons of propane per month.

Not included in this version: food and diet, purchased goods and services, home construction, and electricity outside the U.S. and Brazil. Aviation non-CO₂ effects (contrails, radiative forcing) are not applied, and cabin class is not distinguished.

Business and organization calculator

Structured after the GHG Protocol Corporate Standard. The user selects a consolidation approach (operational control, financial control or equity share) and enters data only for operations inside that boundary.

• Scope 1: stationary combustion (natural gas, propane, fuel oil, kerosene), company-vehicle fuel (gasoline, diesel, LPG, CNG), and refrigerant leakage estimated from kilograms recharged × GWP (screening method).
• Scope 2: location-based electricity with eGRID2023 subregion or Brazil SIN factors, and purchased steam or heat. Market-based electricity is optional and reported separately: supplier-specific factors when provided, certificates at zero only when the quality criteria are confirmed, otherwise the grid average (a residual-mix factor is not included in this release and the result says so). Purchased cooling is listed but not calculated.
• Scope 3: all 15 categories are listed with a status. Calculation methods are available for categories 3, 4, 5, 6, 7, 9: transmission and distribution losses (U.S. only; upstream fuel extraction not assessed), upstream and downstream freight, waste, business travel and employee commuting.

Scope 3 categories without a method (1, 2, 8, 10, 11, 12, 13, 14, 15) are shown as “not assessed”, unless the user marks them not relevant. Categories 1 and 2 usually require spend-based (for example USEEIO) or supplier-specific data and are candidates for a later version.

Sources

• GHG Emission Factors Hub. U.S. Environmental Protection Agency, Center for Corporate Climate Leadership. 2025 edition, published 2025-01-15.
• eGRID2023 subregion total output emission rates (as published in the EPA Emission Factors Hub 2025, Table 6). U.S. EPA. eGRID2023, published 2025-01.
• Average CO2 emission factor of the National Interconnected System (SIN), annual average 2023. Brazil Ministry of Science, Technology and Innovation (MCTI). 2023 annual average, published 2024-02.
• Residential Energy Consumption Survey 2020 averages, cited in EPA “Assumptions and References for Household Carbon Footprint Calculator”. U.S. EIA (as cited by EPA). RECS 2020; EPA page updated 2026-03-02, published 2026-03-02.

Factors reviewed 2026-11-10. When sources publish new editions, factors will be updated and the methodology version incremented.

Factor register

Stationary and mobile fuels

Passenger travel

Freight

Waste (end-of-life treatment)

Electricity grids

Refrigerant global warming potentials (AR5)

Source: EPA GHG Emission Factors Hub 2025, Tables 11–12. HCFCs such as R-22 are not included in Scope 1 totals under the GHG Protocol and are listed as unsupported.

Limitations

• Results are screening estimates, not verified, certified or audited inventories, and are not suitable on their own for regulatory reporting, product claims or assurance.
• Factors are U.S.-centric; outside the U.S. and Brazil, fuel and travel results are approximations and electricity is not calculated.
• Results are not comparable with other calculators that use different boundaries, factors or global warming potentials.
• Upstream (well-to-tank) emissions of fuels and electricity are not included except grid transmission losses.

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