If you are saying that her strips finish at 1.5" in the original quilt, and you want them to finish at 2". You would divide 2 by 1.5 = 1.333333 This would be the factor to use with every finished piece size. The 1/4 inch seams have to be added to the finished size. You can not just adjust the cutting sizes, because you would be upsizing the seams also.
If you want the finished size of the quilt to change from 60 inches to 90 inches, then you should divide 90 by 60 = 1.5. This is your factor.
Therefore, you would multiply the finished sizes of all your pieces by 1.5 to get finished size and then add your quarter seams to all sides, then cut the pieces.
An easier way to look at it is to deduct your 1/2 inch seam allowances from the cutting instructions for each piece. Multiply this number (which is your finished piece size) by 1.5, then add the 1/2 inch seam allowance back, then cut.
The 1.5 inch finished strips = 1.5 x 1.5 = 2.25 + the quarter inch seams, .5 = 2.75 inches.
Example:
A piece that shows as cutting 2 x 6 inches
Deduct .5 from the 2 and from the 6. Adjusted/finished size is now 1.5 x 5.5
1.5 x 1.5 = 2.25; 5.5 x 1.5 = 8.25
Now add the 1/4 seams back. 2.25 + .25 + .25 = 2.75; 8.25 + .25 + .25 = 8.75
Therefore, you would cut 2.75 x 8.75 instead of the 2 x 6 inch piece.
First time I have ever tried to explain this....if anyone sees an error in my calculation, then please speak up. I wouldn't cut all my material based on these numbers. Make sure it does work out.
Last edited by Barb in Louisiana; 02-02-2016 at 01:14 PM.