In Traverse Town's one-and-only Item Shop(ran by Donald's three nephews, Huey, Duey, and Luey), located in the 1st District, there is a quaint weight-scale standing symmetrically upright against a wall, evenly-spaced in-between the purchase counter and the wall of the lower-entrance door, and facing the feet of the turquoise-colored stairs. Hop onto it and engage First-Person Mode, and from here you can see vaguely how much Sora weighs by the little needle pointing just shy of 90 (rather about 75 instead), representing Soras weight. Note: The same effect is not achieved when Goofy or Donald stands on the scale (which is rather difficult to get either of them to do, anyways).