Sand vs stars (& how is this quantifiable)?

Basic the question is, “Is Carl Sagan’s claim true about the number of stars in our universe being greater then the sand on all our beaches?”

I’ve heard that all the sand on all the beaches = or ≠ the amount of stars in our universe. So which is it?

I recently asked an astrophysicist (Laurance Doyle actually, it’s sort of a long story) about this, and he said that all the stars in the universe are much greater in number than all of the sand on this planet. And then something about an order of magnitude of 100.

I really like this idea, but how is it truly quantifiable? And what are some of the maths behind these comparisons? Wouldn’t there be a high margin of error?

I believe it was Carl Sagan who first made this statement. For some it’s just the beaches, and others include all the deserts. Some say all dry sand, excluding wet sand apparently.

‘The total number of stars in the Universe is larger than all the grains of sand on all the beaches of the planet Earth.’
Glen Mackie agrees with Carl Sagan.
Carl Sagan says the stars and sand are equally countless.

Then there are folks like this guy.

How quantifiable is this claim?