Several calculators are available on-line to help individuals calculate their carbon and/or ecological footprints.

The field is a work in progress and the calculators we found were more generic than individual.  Carbon dioxide emissions are the standard for measuring individual environment impact which neglects a lot of areas such as the consumption of non-sustainable resources.  Still the calculators were interesting and did provide a rough estimate of the users' impact. 

Footprintnetwork.org has a calculator that is probably the most fun to use but provides little illuminating output.  Using cartoony graphics, a customized avatar representing the user moves through the landscape, plopping down a house, car, trash, and a food stand sized to represent the users' consumption in answer to each question.

Individual output is calculated in carbon dioxide (CO2) emissions and as the number of planets and the number of global acres needed to support each user's consumption.  For example, I generate 21 tons of CO2 each year and I need 18.2 global acres to support my lifestyle.  If everyone on the planet lived in the same way I do it would require 4.0 planet Earths to support us.  However, no comparative data is provided.  I want to know how I measure up; if I impact the Earth more or less than my neighbor.  No clue on this site.   


Carbonfootprint.com was even less helpful.  This British site asks a few questions in each of several categories - house, auto, airplane flights, secondary use (i.e. recreation); to come up with CO2 emissions in "tonnes."  Again, no comparative data was provided but I was led to a different page and invited to purchase carbon offsets which, in the recommended $65 range, would balance the damage I am doing to the planet.  The offset money is used to plant trees, mostly in third-world countries.

The best site I visited was provided by the Environmental Protection Agency (www.epa.gov/climatechange/emissions/ind_calculator.html).  It is a carbon footprint calculator rather than an ecological measurement, ignoring the impact of food and water usage.  The calculator estimates CO2 emissions in a number of categories including heat, transportation, and trash disposal and compares the estimates for the user in each category to national averages.  For example, I generate 17,262 lbs of CO2 through electrical consumption compared to an average of 16,290.  However, I generate less than one-quarter the average emissions of 12,100 lbs from operating a vehicle.

The calculator gives credit in CO2 pounds for waste recycling and then computes an emissions total.  The national average is 45,100 lbs.

This calculator also estimates the reduction in emissions you can achieve through some simple conservation measures.  Are you willing to install a few energy-saving light bulbs?  How many?  Pick the number four and you will reduce your emissions by 400 lbs.  Turn down the heat at night during the winter by 5 degrees and cut usage by 285 lbs.     

Two other sites worth mentioning are http://www.ecobusinesslinks.com/ and http://www.recyclingcenters.org/.  Each provides links to a number of calculators for specific purposes - electrical consumption, airplane travel, commuting, auto mileage, appliance consumption, etc.

New standards for determining ecological footprints are due to be announced in 2009 and perhaps these will lead to more precise and less generic calculators.