You have now made eight HSTs!
To get the prefect HST that has oops room, you need to do a bit of math… I know, just great isn’t it… Well, don’t get too down hearted, because there are some magic numbers to remember for your calculations.
Example: if you want to make a finished block the size of 8 inches, we calculate the finished size 8 inches plus 7/8th inch to make HSTs.
To make HSTs with oops room, add another ½ in to your block size, then when you have finished sewing your HST block you can square it up to the size you require for your quilt (this method only makes two half square triangles).
When using the hour glass block to make HSTs, use this calculation:
Finished size + 7/8 x 2+ 2 1/8 + ½= size square you need to cut (including oops room).
Example: in the picture above my finished block is 5 in. 5+ 7/8= 5 7/8 x2= 11 ¾ +2 1/8= 13 7/8 +1/2= 14 3/8. I need to cut two fabrics of contrasting values to 14 3/8 inches square. This will yield the size of the HST I want. This formula will size any block you want.
When following a pattern, they don’t always include oops room. If you want to work the pattern as written, go for it. If you want to include oops room, you need to find out which fabric cut will be the HST, and add a ½ in to the cutting requirements. Example: the two HST method below: