Carbon Footprint Calculator
Estimate your annual household carbon footprint from travel, home energy and diet.
Formula and sources updated · Data sources · 3View algorithm, constants and default inputs (JSON)
About this calculator
This is a rough estimate for the categories shown, not a full personal footprint or emissions inventory. Grid intensity is user-entered; flight and diet factors are broad assumptions that may not match your route, region or household.
Worked example
calculated with the default values below
Car miles per year 10,000 mi · Car fuel economy 30 mpg · Short-haul flights per year 4 · Long-haul flights per year 1 · Electricity use per year 8,000 kWh · Natural gas use per year 600 therms · People in the household 3 · Diet Average omnivore · Grid carbon intensity 0.4 kg CO2/kWh Car emissions 2.96 tonnes/year · Flight emissions 2.60 tonnes/year · Home energy emissions 6.38 tonnes/year · Diet emissions 6.00 tonnes/year · Total household footprint 17.94 tonnes/year · Per person 5.98 tonnes/year · Compared to the global average Rough estimate for listed categories only; not a full emissions inventory
Data sources
Disclaimer
These calculators give general estimates. Sizing, pricing, availability and standards vary by brand, retailer and country, so treat the output as a starting point and confirm it against the seller's or authority's own figures.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
E = C + F + H + d·h, C = 8.887·m ÷ (1000·mpg), F = 0.25 f_s + 1.6 f_l, H = (g·kWh + 5.3 t) ÷ 1000
- E
- Annual footprint (t CO₂e)
- C
- Car emissions
- F
- Flight emissions
- H
- Home-energy emissions
- d
- Diet emissions per person (0.9–2.5 t)
- h
- Household size
- m
- Miles driven per year
- mpg
- Fuel economy (miles per gallon)
- f_s
- Short-haul flights per year
- f_l
- Long-haul flights per year
- g
- Home electricity use (kWh/year)
- t
- Natural gas use (therms/year)
This rough model adds entered car fuel use, fixed flight factors, electricity × user-supplied grid intensity, natural gas at 5.3 kg CO₂ per therm, and preset diet factors. It includes listed categories only and is not a complete footprint or inventory. The gasoline factor 8.887 kg CO₂/gallon follows the U.S. EPA tailpipe factor; EPA estimates are approximate.
Frequently asked questions
What do these footprint numbers include?
The estimate includes only the modeled car fuel, flights, home electricity and gas, and a preset diet factor for the household. Flight distances and diet factors are broad assumptions; grid intensity is supplied by you. It excludes other travel, purchases, services and many lifecycle emissions, so use it for rough comparisons only—not formal reporting or a complete personal footprint. The 8.887 kg CO₂ per US gallon gasoline factor follows EPA’s tailpipe factor; EPA describes its own footprint estimates as approximate.