This chart explains how we came up with the figures and retail costs used for calculating the value of your library usage.  Some values are estimates and/or averages based on retails costs of 2007.

Item	Estimated Retail Value	Values Explained - January 2008
Book Borrowed	$20.00	Estimated average cost between hardcover & paperback
Magazine Borrowed	$4.00	Estimated cost to purchase a popular periodical issue
Movies Borrowed	$4.00	Sample video rental at video store
Book on Tape Borrowed	$30.00	Average price between downloading and purchasing an audiobook
Museum Passes Borrowed (per person)	$8.00	Admission price for one adult to the Christa McAuliffe Planetarium
Magazine Use in Library	$4.00	Estimated cost to purchase a popular periodical issue
Interlibrary Loan Materials	$25.00	Average cost for loans in New Hampshire
Meeting Room Use per Hour	$50.00	Estimate
Adult Programs Attended	$15.00	Average cost for one adult to attend a show or program
Children's Programs Attended	$12.00	Average cost for one child to attend a show or program
Hours of Computer Use (i.e. Internet,  MS Word, etc.)	$12.00	Sample hourly rate at a copy center
Newspaper Articles Viewed Online	$2.50	Cost to download an article from one of New Hampshire's newspapers
EBSCO Database Searching (number of months used)	$20.00	Minimum cost for monthly access to sample online database
Reference Questions	$8.00	Estimated cost per question

The Chesley Memorial Library's Library Use Calculator is based on the spreadsheet developed by the Massachusetts Library Association and adapted for web use by the Maine State Library and the Chelmsford Public Library.