please tell me friends
Well, page is not a physical thing so we can weigh it..
However, you can know its value from traffic, page rank etc.
Of course we can not weight a web page, but actually it's size has a great meaning. If the page's weight is small - it will load faster, which of course it's good. So you need to try to reduce the weight if possible. Lower page load times create more comfortable visitors.
For example the page which weights 100 kb can load from 3 to 62 seconds (it depends on the speed of connection) and the page which weights 20 kb from 1 to 12 seconds.
I think you need to split that out into mobile web size and desktop size. However even if the page is 2mb, but it loads within a few seconds, does it matter?
I think you are talking about total size of webpage. It's not defined but you should take care for few things like utilize less numbers of css and js on page as much as possible, use css sprite to combine multiple images, do no use very high resolution picture on page etc etc...