I use the same method as Robin - it allows for a little extra, but not too much!
Best wishes,
Mike

Thanks so much for ya'lls input!

Hi Martya!

This is the formula I use:

finished size plus 1 inch for each fabric color.

Cut each fabric square that size.

Layer fabric squares, draw the line, sew on either side of the line, cut apart

Iron and trim to the unfinished size. Voila!

Works every time ... in fact just made some in a size I don't normally make and it worked like a charm.

If you insist on doing the traditional method ... just cut the squares in half before you sew ... then be careful with the bias edge.

Good luck!
Robin

Hi Martya -

Rosemary's formulas are for getting the sizes exactly (with some rounding). If you want to make them bigger so you can cut them down, just add whatever margin you want to the numbers Rosemary has provided.

Nancy

If you are going to cut a square into 2 half square triangles you need it to be 3/8" larger.
example:
For a finished 2" square you cut 2 1/2" - 2" plus 1/2" seam allowance.

For a finished 2" square of half square triangles you cut your squares 2 7/8" - 2" plus 1/2" seam allowance around the outside plus 3/8" for the seam allowances down the middle. Then cut in half diagonally

For a finished 2" square of quarter square triangles you cut your squares 3 1/4" - 2" plus 1/2" seam allowance around the outside plus 3/8" for the seam allowances for one diagonal cut plus 3/8" for the seam allowances for the other diagonal cut. Then cut in quarters diagonally.

I've added on the extra about quarter square triangles as it is a natural progression, even though you didn't ask about them.
One exercise I have done in the past is to draw out a triangle on graph paper, added on the seam allowances and then drawn the second triangle on to see how it makes the square, this can be useful to get a visual memory of what you are trying to achieve and remember.

Does anyone know the formula for making the 1/2 squares bigger so they can be cut down? Thanks!