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Energy and the Environment

Frequent Questions: EPA’s Greenhouse Gas Equivalencies Calculator

This page answers some of the most commonly asked questions about the Greenhouse Gas Equivalencies Calculator. Click on the questions below to view the answers.

Assumptions and Sources

Extending the Calculator

  • Q: How do I calculate an ecological footprint?

    A: Ecological footprints typically include a carbon footprint that represents the area of forest land that would be required to sequester CO2 emissions from human activities. According to the Calculations and References page of EPA's Greenhouse Gas Equivalencies Calculator, one acre of average U.S. forest sequesters 1.06 metric tons of CO2 annually. Using that figure and assuming you have calculated your CO2 emissions, you can estimate the number of acres of forest that would be required to sequester those emissions.

  • Q: How do I calculate average household emissions?

    A: EPA does not provide an official estimate for average household emissions, but there are two ways you could derive this information from EPA sources:

    • EPA’s Inventory of Greenhouse Gas Emissions and Sinks provides a breakdown of emissions by sector, including details for the residential sector. If you divide the total by the number of households in the United States, you will obtain an estimate of residential emissions per household. Note, however, that this does not include transportation. Transportation-related emissions are in Table 2-13. U.S. households own an average of 1.9 vehicles per household.
    • EPA’s Household Carbon Footprint Calculator provides values for average emissions from households for specific areas such as vehicles and specific fuels. These values could be built up into an estimate, although note that this does not include sources such as air travel or food. The Household Calculator was designed primarily as an educational tool and does not produce precise estimates.