Calculating what you should be reimbursed for mileage is easy with TravelBank. Head into Expenses > Select the blue + icon and select Mileage from the menu. This will create a new expense card for mileage, where you can enter the number of miles driven, plus the description of the trip purpose and a photo of your route if necessary. 

The mileage calculator is automatically set to the current IRS rate of $0.58. 

See the short video below for a walkthrough of how to add a mileage receipt on iOS: