Measure is a calculated ratio that reflects the overall annual use of the library's total collection of materials. The measure will increase or decrease relative to the number of times library materials are checked out. Higher numbers indicate customers are finding items they want to check out from the collection. This measure is a primary professional library measure that can be benchmarked with peer libraries of varying sizes. The rate is a formulaic calculation based on the cummulative total of items checked out for the fiscal year and the the total number of items in the library's collection. The calculation is affected (either positively or negatively) by both the number and subjects of items added to and removed from the collection. Because the factors in the calculation are in the millions, the turnover rate is often affected in minute increments. The target of 3.19 is based on increase from previous year rate.

Deborah Duke calculates the measure based on circulation and holding reports run from the Polaris ILS and then reports them to Paul Orr. The Public Library Data Survey also calculates this measure based on annual data reported. The PLDS statistics are available through the Counting Opinions reporting software.

Actual = (Total annual circulations / total library collection holdings)

HV = 3.19

LV = 3.15