Caffeine is a widely consumed stimulant, and caffeine-containing products are increasingly available on the market. Few tools are available to capture caffeine intake, particularly among young adults. To estimate caffeine consumption in the previous 24 hours, the 24-Hour Caffeine Intake Recall (CIR-24) was modeled after the Automated Self-Administered 24-Hour Dietary Assessment Tool, using a brand-specific database of caffeine-containing foods, beverages, and supplements.