AIR TRAVEL OFFSET GUIDE: You should purchase 1 carbon offset for every 5000 miles you travel by air.
To calculate your miles, we recommend using the air miles calculator at webflyer.com. (www.webflyer.com/travel/mileage_calculator)
One Carbon Offset represents the reduction of greenhouse gases equal to one metric ton (or 2,205 pounds) of carbon dioxide equivalent (CO2e). Each BEF U.S. Carbon Offset is third-party verified to prove that real, additional, permanent, verifiable and enforceable emissions reductions have occurred. Your purchase, combined with that of other BEF partners, represents a significant funding source that helps ensure continued innovation and development of carbon reduction projects and technology.
Methodology - BEF uses an average between the short, medium and long haul coefficients established by Defra (Department of the Environment, Fisheries and Rural Affairs, London, England, UK). (http://archive.defra.gov.uk/environment/business/reporting/pdf/091013-guidelines-ghg-conversion-factors-method-paper.pdf)