Abstract: Devices and techniques are generally described for sample size prediction for online activity. In various examples, first data related to a first sample of users interacting with an online service during a first time period may be received. In some cases, first key performance indicator (KPI) data related to the first sample of users' interaction with the online service may be received. A predicted sample size of users that will interact with the online service for a second time period following the first time period may be predicted. A predicted statistical power may be determined using the predicted sample size. In some examples, a minimum amount of time to route traffic to the online service may be determined based at least in part on the predicted statistical power.