SATURN RINGS:

The A-ring ends at about 137'000 km from Saturn's centre.
Such a distance includes the major part of the luminous rings.

length = 137'000 km, thickness = 0.1 - 1 km (see source).

Ratio of 137'000 : 1



SHEET OF PAPER:

To easily estimate the thickness of one single sheet of A4 paper,
take a block of 500 sheets: it has a thickness of about 5 cm, so
one sheet is 5/500 = 0.01 cm thick.

length = 28 cm, thickness = 0.01 cm

Ratio of 28 : 0.01 = 2800 : 1



COMPARISON:

137'000 / 2800 = 48.9

Saturn rings are (proportionally speaking) about 50 times thinner than a sheet of A4 paper!