Calculation Methods

We calculate emissions from electricity generation with the EPA’s eGRID emission factors based on 2021 data published in 2023, using the US average electricity source emissions of 0.857 lbs CO2e per kWh (0.3712 kgs CO2e per kWh).

There are 10.16 kgs of CO2e per gallon of home heating oil. (Source: U.S. Department of Energy)

There are 0.00531 metric tonnes of CO2e per 100 cubic feet (CCF) of natural gas. (Source: U.S. Department of Energy) 

There are 0.00576 metric tonnes of CO2e per gallon of propane. (Source: U.S. Department of Energy)

Unleaded automobile gasoline emits 8.78 kgs CO2e per gallon. Diesel fuel emits 10.21 kgs CO2e per gallon.

CO2 emissions for coach/economy air travel vary by length of flight, ranging from 0.13 kgs CO2e per passenger mile to 0.209 kgs CO2e per passenger mile, with higher emissions for shorter flight segments. Our calculator uses a simplified factor of 0.2 kgs per passenger mile.

The CO2e emissions for long distance trains (i.e., intercity rail) is 0.114 kgs per passenger mile.

Product shipping emissions is calculated by the total number of parcels multiplied by the average parcel weight and average parcel shipping distance then by the applicable emissions factor per ton-mile.

Ground/truck shipping emissions factor is 0.213 kgs/ton-mile
Air shipping emissions factor is 1.1778 kgs/ton-mile
Rail shipping emissions factor is 0.022 kgs/ton-mile
Ocean/water shipping emissions factor is 0.0418 kgs/ton-mile

The average person’s diet contributes 2,545 kilograms CO2e to the atmosphere each year. By dividing by 365, it is deduced that the average person’s diet contributes, on average, 7 kg CO2e a day from their meals. This calculation is based on an average US, non-vegetarian diet. The emissions for food preparation are not included in this calculation. (Source: Johns Hopkins Bloomberg School of Public Health, Average of Table 3).

Emissions associated with a one night stay in a hotel room are calculated at 15.13 kg CO2e per room day for an average US-based hotel (budget through mid-scale). For upscale US-based hotels, that include restaurants, meal service and meeting space, emissions are calculated at 26.6 kg CO2e per room day. (Source:Environmental Protection Agency, CHP Potential in the Hotel and Casino Market Sectors, prepared by Energy and Environmental Analysis, Inc. for EPA.) More specific hotel room-night emissions can be calculated by property or location using the Cornell Hotel Sustainability Benchmarking (CHSB) study and this online hotel emissions calculator: https://www.hotelfootprints.org/.

All emissions factors in the “Office Emissions” category are based on annual (12 month) emissions. Emissions factors for energy (kWh) are based on state-based figures from the EPA eGRID

There are 0.00531 metric tonnes of CO2 per 100 cubic feet (CCF) of natural gas. (Source: U.S. Department of Energy)

Emissions factors for electricity by your monthly bill are based on state based figures from the EPA eGRID to get the state-by-state prices for energy, and the emissions factors are generated from the Department of Energy’s Energy Information Administration. On average across the US, electricity sources emit 0.818 lbs CO2 per kWh. State CO2 emissions per kWh may vary greatly in accordance with the amount of clean energy in the energy supply.

There are 10.16 kg of CO2 per gallon of home heating oil (diesel fuel). (Source: US DOE 1605(b) Voluntary Reporting of Greenhouse Gases Program.)

There are 0.00576 metric tonnes of CO2 per gallon of propane. (Source: U.S. Department of Energy)

Server emissions are calculated assuming an average 251 watt server (source: Vertatique) with 95% up time. The energy usage of each server is then multiplied by state based emissions factors.

Fleet emission calculations assume the national average of 25.2 mpg and the emissions factor of 19.4 lbs CO2 per gallon of gasoline consumed. Fleet emissions for delivery vans and trucks assume an average of 18.8 mpg. and the emissions factor of 22.2 lbs CO2 per gallon of diesel consumed. Fleet emissions big rigs assume an average of 5.4 mpg and the emissions factor of 22.2 lbs CO2 per gallon of diesel consumed. (Source: Transportation Data Energy Book 2015 – Quick Facts)

All travel emissions factors sourced from EPA Emissions Factors for Greenhouse Gases Inventories 2022.

• Short flights are calculated to be under 300 miles one-way with emissions of 0.209 kg CO2e per passenger mile
• Medium flights are calculated to be 300-2300 miles one-way, average 1500 miles, with emissions of 0.13 kg CO2e per passenger mile
• Long flights are calculated to be > 2300 miles, average 3,000 miles one-way with emissions of 0.165 kg CO2e per passenger mile
• Train trips are calculated 0.114 kg CO2e per passenger mile
• Subway trips are calculated 0.1 kg CO2e per passenger mile
• Bus trips are calculated at 0.059 kg CO2e per passenger mile

All emissions figures from EPA Emissions Factors for Greenhouse Gases Inventories 2022.

• Commute by Car – assumes 0.334 kg CO2e of gas consumed per mile and a two way commute 245 days a year. (The kg CO2/vehicle mile average of both passenger car and light-duty truck.)
• Commute by Intercity Rail (Amtrak) – assumes a two way commute 245 days a year, with 0.114 kg CO2e emitted per mile.
• Commuter Rail – Assumes a two way commute 245 days a year, with 0.14 kg of CO2e emitted per mile.
• Commute by Transit (tram, subway) – assumes a two way commute 245 days a year, with 0.1 kg of CO2e emitted per mile.