To calculate the days before a certain date, you can use subtraction and the TODAY function. In the generic version of the formula above, date is the later date. cdate Given a certain date, whats the easiest way to determine how many days until that date (in PHP)? I am trying to build a count-down widget. Let's say you want to find out how many days there are between two project dates or find out how many shopping days there are before a holiday. To count the.