Which Week?
Type a date, a day of the year (a number between 1 and 366) or a week number. Then click the button Calculate on the same line.
For the day of the year and for the week number you have to type the year (four digits) too.
Do you find it annoying that the week numbers in MS Outlook don't correspond with the ones in your diary? The tool on this page gives you a solution.
In the European countries (except the United Kingdom) the week numbers are attributed according to the ISO 8601 rule. That means that every week starts with a Monday (contrary to the United States, where every week starts with a Sunday) and that the first week of the year has to contain at least four days (or formulated otherwise: the first week of the year is the one that contains the first Thursday of the year).
The American version of MS Outlook on the other hand is configured default so that the first day of a week is a Sunday and that the first week of the year has to contain the 1st of January. Most people adapt their configuration in such a way that Monday becomes the first day of a week, but they keep the default configuration for the first week of the year. (In fact, in that way they follow the rule of the United Kingdom for the numbering of the weeks.)