what is this seam allowance is it smaller than 1/8th?

I do a thread or 2 less than a 1/4 inch.

1/4 is actually equal to 2/8

So 1/4 is bigger than 1/8

Imagine you cut your pumpkin pie into 8 slices. One slice is equal to 1/8. If you cut your pie into 4 pieces, 1 piece is 1/4.

:)

Oh, and a scant is just a hair smaller than 1/4. Roughly a thread's width.

so what is the difference of doing a full 1/4 seam allowance than the scant 1/4 does it REALLY matter? or can i just use the 1/4in seam allowance.

I find that it totally depends on the pattern that I am making...

I wouldn't worry about scant/not scant. Here's a link on how to check your
seam allowance. Make sure to use the same fabric, needle and thread than
your project. You can move your needle slightly to the right or to the left
until you get the right width. If you can't move the needle then you can
stick a piece of tape or moleskin on your machine as a guide.

How to Test Quilt Seam Allowances for Accuracy
http://www.suite101.com/content/how-...ch-seam-a58429

I find what works for me is to cut three strips of fabric two inches wide by five inches long.

Sew them together.

Press.

If my square is five inches by five inches, I'm doing good.

If it is less than five inches wide, the seam allowances are too deep/wide.

If more than five inches wide, make the seam allowances narrower.

Depending on how one places one ruler, etc., "your" two inch strip may be a tiny bit narrower or wider than "my" two inch wide strip.

So - this little sample/test can really save one a lot of aggravation.

A "scant" quarter inch is such an annoying instruction to me.

In my mind it is somewhere between 3/16 of an inch and 15/64 of an inch.

1/4 = 2/8 = 4/16 = 8/32 = 16/64

I've found that if you have lots and lots of pieces in a block, and it is a big block, by the time you get to end outer piece it may be too small. I usually use a scant 1/4, because it give you a schosh more in size. TRhen, if it is a hair too big, it can be trimmed off.

Mine is just a thread or two short of 1/4 inch. It gives me wiggle room if I need it.

The scant can make a big difference in HSTs (half-square triangles) and using a full 1/4" can lead to lost points.

I was in a swap exchange where the blocks had to be 12.5" and when I used my regular seam allowance, some blocks came in a bit smaller, so I had to resew them. Not fun! Now I spend more time measuring as I go so I don't have any do-agains.