You need a Proportional scale. i don't think increasing by percentage will be accurate. Close enough for a quilt block though.

It's a beautiful block. Thanks for sharing with us.

So just to brush off my brain cells....

26/12 = 2.1667 so all your measurements would have to be multiplied by 2.1667 to give you a 26" block. Much easier to multiply by 2 and add that 1" sashing, right?

Or am I wrong about multiplying each measurement by 2.1667?

If you had a 26" block and wanted to shrink it down to 12" you would divide 12 by 26 to get your multiplier for the sides..... I think.

You need to increase the finished size of each piece and then add back they seam allowances Beautiful block

Thank you all for your input....I will double the sizes on the pattern as suggested. Have a wonderful day!💕💕💕

be sure to consider seam allowances. A double size block still has only one seam!! A 2.5 inch block will be 4.5 since finished is 2 inches, double to 4, then add seams. And border would indeed be 1 1/2 inch strips to finish at 1 inch on all sides.

DebLuvs and CJ -- it is not a straightforwards multiplication of the 2.5 block measurements. Yikes! Thank you! My method would take a 2.5 in measurement andupsize it to a 5.something square so ultimately it would be much bigger than 26 inches. Time to do some more brain dusting! What a great brain teaser! Double the size of the finished block then add seam allowances. Good thing I have never tried to change the size of a pattern.

The .5 is the seam allowance (.25 around each edge of the block) if you are just doubling the pattern, you would only double the first number. A 2.5 block doubled becomes a 4.5 block. A 4.5 block doubled, becomes an 8.5 block, doubling the 8.5 block becomes a 16.5 block and so on.

Note: I'm just showing the math to double a block.