There is method for doing this in
DateTime
class itself, see the next example:
DateTime utcDate1 = date1.ToUniversalTime();
DateTime date2 = utcDate1.ToLocalTime();
This solution works on windows desktop application, but not in the case of web application when the clients could be from any country and your code run on the server. So in this second case you should see the next link and you have to use Javascript in you web page:
http://www.w3schools.com/jsref/jsref_gettimezoneoffset.asp[
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