There has been research done by Steven LaBerge in this area and he has concluded that for the most part, the actual time expired in reality and what the dreamer thought are about the same.
I must be odd as its not like that for me.
In my dreams I often have "no sense of time at all" or experience more time passing by then in real life eg end up thiking Ive been away from physical awareness longer then I have. eg I can have what I think is a 5-10min LD and think Ive been asleep at least that long but then wake myself up and find that only 2-3 mins at the most have passed in real life.
Also If I think of my physical body.. I can get no good awareness of how long its been asleep for or what time it is (that is unless Ive gone into a LD throu a WILD in which I didnt loose awareness at all on dream entry but my dream time is still running different to my real life time).
When im doing astral projection thou.. if Im in the normal earth astral, I can then make a very good correct guess of how much real life time has passed. I have real time awareness then.