why is origami paper a square? why can't it be another shape, like a circle?

Question

i once saw some patterns made out of circles; but i meant why aren't patterns developed out of a different shape

Answer 1

Many patterns do start with other shapes too.
some need six equal sides to make a shape with six sides, like a daffodil, others start with A4 sheets because they are handy. Most paper sold in Europe, (and maybe also Japan) is now in A4 or the other A sizes.
http://www.origami.34sp.com/diagrams.htm

But square is rather easy to make, even without rulers and such, as long as you know your basics. (Before paper was sold in nice squares people would know those basics, now nobody does anymore.)

And this site has as first listed model how to make an A4 (shaped) paper out of a square.
http://dev.origami.com/diagram.cfm

Many paper planes, (also a kind of origami) are made out of the paper that was at hand, not nice squares.

There are circular models, but I find them uninspiring, so I never used all of those expensive round sheets I bought.

Answer 2

Tradition.

When paper was first being made it was made in squares and so when origami was first developed they only had square paper and didn't have a need for anything else.

Coming up with patterns that do use round paper would be cool but not traditional so I am sure it is out there just not as common.

Answer 3

Because all of the patterns begin in a square. Otherwise they will not fold correctly.

Answer 4

They are. There a several designs for origami with money, a rectangle.