Just tried this out with my quilting friends after we saw a video on line. It seems you cut your blocks 2" bigger than your want your triagles to be. 5" block gets you 4 3" HST.
The video said not to stress about stretching out of shape.

I have a ton of triangles to do and they will end up being a l2 block or l2 1/2 unfinished block, what size would I need to cut the squares, I think this is neat and I have lots of sizing already LOL
Thank you for this tut its fabulous

That's a great idea! Thanks for the Tute! Bueatiful squares btw

I also need the formula for bigger squares 9, l0 etc. Thanks again

Great information.

Hi Oma66:
I love halfsquare tri's. Thank you so much for sharing this with we who had not heard of this method. What a
great idea.

Not that it matters but the Gma below stands for being grandmother to 6 (triplets, twins and a single), who call me G-ma (short for Grandma), and the GG is for being great-grandmother to four who know me as GeeGee. The last four couldn't call me Grandma because that's what they call my daughters. Anyway, quicker half-square triangles will make 4 new quilts (they're no longer infants) go much faster! All I have to do is use 4 different combos of color.
Thanks again! Gma-GeeGee

The math for this is start with the squares 1 1/2 times larger than the finished size.

2 times the diagonal of the size you want divided by 1.414 = exact size to cut large square.


If you wanted a 4" sq double to get the diagonal which would be 8" divide by 1.414 or (1.5 and trim later) = size of starting square to use.

In case I forget the math look at the diagonal on the cutting mat and count the squares.

This is what I mean by looking at the mat. If I wanted a 9" sq finished the starting sq would be 13. Add 1/2 total for seam allowance.

WOW>>>that easy? Amazing....thank you for that tut! Bookmarking it and also saving the pics, just incase! Thank YOU!!

I heard about this from a friend but could someone provide numbers to make different sizes. Right now I take 2 pieces put right sides together to check what size I get; for example: 12-1/2" will make 4 each- 8 1/2. This also makes a 16 1/2 pinwheel.