Amount of required gfx memory

[Zacker]

Is the size of the texture files equal to the amount of required gfx ram? If a vmt file e.g. take up 4 megs of hdd space, will it then also take up 4 megs of gfx ram?

I need to know this for specifying the specifications of the textures sizes in my mod. If it is possible just too look at the vmt size, then it should be fairly easy to find some good sizes.

You could of course just go with the usual sizes of other games, but that is not nearly as fun as figuring it out yourself.