In Experiment 1, we conducted a survey in which we asked a sample of N = 762 participants explicitly about their preferences regarding reimbursement and experimental duration of web-based experiments. Participants significantly prefer donations and raffles over other forms of reimbursement in 5-minute experiments. When experiments take 30 minutes or longer, participants significantly prefer direct payment. This finding applies to 15-minute experiments, too, if only data of PayPal account holders is analyzed (75.23% of our sample). In Experiment 2, we implicitly measured the preferences of N = 189 participants by letting them choose between experiments with different durations and forms of reimbursements. As in Experiment 1, direct payment was the preferred reimbursement in longer studies. The most popular choice of duration and reimbursement was to receive direct payment for an experiment of 60 minutes, which was selected by 57% of all participants.