Put Steve in a 1x1 hole and measure the wiggle room.  ALL the room - WiggleRoom = Steve

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In a 1x1 hole, I pointed the camera straight down and moved from corner to corner.  Regardless of corner or orientation, the crosshairs pointed at the farthest point of a 5x5 square from the corner.

16 = 5 + 6 + 5

That's 16 total square width, 5 for the each side of Steve, and 6 for the wiggle room.

Front/back/left/right, the closest you can get to a wall is 5.  This test is unable to confirm if Steve is 10x10 square, or a 5 radius circle.