Abstract CPM or cost per thousand impressions is the prevalent metric used for selling online display ads. In previous work, we have shown that the exposure duration of an ad has strong effects on the likelihood of an ad being remembered [Goldstein et al., 2011], with the ?rst seconds of exposure having the greatest impact on memory. Because an ad pricing metric that is based on both time and impressions should be more exact than one based on impressions alone, the industry has good reasons to move towards time-based advertising. We address the following unanswered question: how should time-based ads be scheduled? We test and present one schedule that leads to greater total recollection, which advertisers want, and increased revenue, which publishers want. First, we ?nd that presenting two short, successive ads results in more total recollection than presenting one longer ad of twice the duration. Second, we show that this effect disappears as the duration of these ads increases. Together, these ?ndings suggest a form of timebased ad pricing that should appeal to advertisers and publishers alike.