What does infinate mean?
greater than any assignable quantity or countable number.
What is the range of measurement that can be taken from the smallest possible length to the largest possible distance?
Since the largest possible distance is infinate the range of measurements is infinate. If you mean what is the largest defined unit of measure it's the gigaparsec, and the smallest is Planck Length The range of measurements of length that HAVE BEEN made is roughly 10-19 meter to 14 billion light years ... a ratio of about 1.32 x 1045 . That's a wide range.