Lady Romana is quoted as saying a TARDIS weights 5x10^6 kilograms, but I've also read that she was mistaken in this or that she was referring to the inside.
The Doctor's TARDIS has been moved a number of times and has landed on soft ground and not sunk in at all. This indicates the full weight of the interior is not felt from the exterior. But in The Parting of the Ways, Rose, Jackie, and Mickey use a large truck with chains to free up part of the interior of the TARDIS, and when they pull with the truck, the TARDIS doesn't just get pulled along on the ground, so, at least when the door is open, there's some connection between the weight inside and the outside shell.
I've searched for this and Romana's answer is the only one I find, but if that were true and it weight that much on the outside, people could not pick it up and move it.
How much does the Doctor's TARDIS weight from the outside?