Internal double doors...standard size??

Hi,
Am planning putting double doors from our kitchen to dining room.
The thing is i havent even looked @ doors and am not sure if i can even afford to buy them just yet.
However now is a suitable time for me to cut the opening in the wall.
Is a standard opening size 1.8M * 2.1M?
Obviously there are bigger and smaller opes but if i know a standard one i will just go with that and worry about picking doors at a later stage.
(basically it suits to make a mess now that would be associated with using a consaw indoors!!)
Cheers and i understand there may not be an easy answer.
many thanks,
Marty

Found this:
http://distinctivedoors.co.uk/doorframes.htm#DFC7836
It lists standard door frame packs.

Cheers Richard...thats purfect!

I am about to do exactly the same job! It's totally up to you what size you use, but most people use a narrower door when used in pairs. However I am planning to use two standard width internal doors (765mm) which will be half glazed.