I think they are 64 tall x 32 wide/deep. Is this correct
what size are players?
Player Dimensions:
The player model’s actual size is a bounding box 30 units by 30 units square with a height of 56 units. In the game world, eight units roughly equal one foot (30.5 cm). From this, we deduce that the characters are a heroic 7 feet tall (2.13 meters).
And i build doors ever 96 x 64…its optimal!
(NdK) 
those are old dimensions from Q3 apparently and aren’t true for ET
follow this thread
http://www.splashdamage.com/forums/viewtopic.php?t=5300
and
http://www.splashdamage.com/forums/viewtopic.php?t=2576&highlight=player+size
BTW, a spawnpoint entity is exactly player size, so you can use them to check things in the editor.
OK, here are the optimally sizes…
Person = 72 units
Door = 84/96 units
Room = 128 units
(NdK) 
You’ll need a gap of at least 72 x 36 x 36 to fit a standing ET player (I think; it’s been a while now).
ET uses a rough scale of 1 unit = 1 inch (2.54cm), but the combination of fov, player height/jump height and screen aspect ratio are a little icky, so it’s useful to scale things up somewhat to make them look the right height in first person. 84 units would be a seven foot high door (which is about right), but it looks way too small in game, so we tended to use 96/104 (and 112/128 for really big doors).
If you’re making a doorway, make sure it’s at LEAST 64 units wide, otherwise players will get caught on it trying to squeeze through (this is another reason why we used slightly taller doors - it keeps the proportions balanced).