Everyone needs a good medical calculator on their smartphone, and MedCalc is my personal favorite based on the plethora of built-in equations. The app has a very intuitive interface that can be easily navigated by users with any level of experience. In addition, equations are organized by subject, alphabetically, and allows the user to easily mark his or her “favorites” for quick reference. Some of the most useful tools that I have found include the opioid conversion tool, the dermatome distribution map, and the ISS calculation. The app is also offered as MedCalc Pro for iPad and includes a full-size HD version with additional resources. At $0.99 or $4.99, this app is a good option for someone that does not yet have their favorite medical calculator app.