18-Week Calculator is a simple but effective tool that assists NHS staff calculate the 18-week period from a given date. The user selects the start date and can then add any number of “pause days” and the 18-Week Calculator does all the fiddly calculations and displays the last day of the 18-week period. The App runs on both iPad and iPhone (IOS 8.0 and higher), is easy to use and quickly mastered.