Circulation figures represent the number of individuals who receive a publication through either subscription or store purchase. The number of copies distributed to these original subscribers or purchasers is known as primary circulation and is the basis for the magazine’s rate structure. Circulation fluctuates from issue to issue, particularly for magazines that rely heavily on retail or newsstand sales. Many publications base their rates on guaranteed circulation and give advertisers a rebate if the number of delivered magazines falls below the guarantee. To minimize rebating, most guaranteed circulation figures are conservative; that is, they are set safely below the average actual delivered circulation. Advertisers are not charged for any excess circulation.

Many publishers became unhappy with the guaranteed circulation concept, since it requires them to provide refunds if guarantees are not met but results in a bonus for advertisers when circulation exceeds the guarantee. Thus, many publications have gone to a circulation rate base system. Rates are based on a set average circulation that is nearly always below the actual circulation delivered by a given issue but carries no guarantee. However, circulation is unlikely to fall below the rate base, since this would reflect negatively on the publication and make it difficult to attract advertisers at prevailing rates.