The GrowthCurves app is useful for researchers working with cell cultures or bacterial cultures, as it provides an iPhone-portable lab notebook and spreadsheet to record optical density (OD) readings for your cultures at different time points. (Users specify sample names and the date and time of each reading.) The app then takes these readings and automatically generates growth curves for your cultures. In addition to the graphing feature, the app features a calculator with four parameters: doubling time, starting OD, total growth time, and final OD. Users input any three parameters and the fourth is automatically calculated. All of the user’s data is organized into individual projects within the app’s “journal.” The entire journal can be emailed and subsequently emptied.