Jelly Roll Blues (and Purples)

When my friend Julie and I were at Spotlight picking out the fabric for quilt 14, I found 3 "jelly roll" bundles that were marked down so low I couldn't believe my eyes.  Two blue and one purple (one of each shown here):

Only $4 each!  Who could resist?  Now, I'll grant you, there's not a huge amount of fabric in these rolls: 25 strips 2.5 inches wide and 42 inches long - that comes to about 1.5 meters of fabric, not a huge amount. Still... $4?  Gotta have 'em for that.

Each roll has 6 prints (four strips of each print). I love doing log cabins, and well, there you go. I sat down with my quilt design software and worked out this design:

 It took no time at all to whip together the blocks. No fuss, no muss:

One jelly roll gave me 7 blocks and some scraps. Thankfully, I did buy 2 rolls of blue, so here's the log-cabin blocks (no, I haven't sewn them together yet...):

Now for the headache part. I need to buy fabric for the spaces between the log cabins on the edge. How much to buy - and how to cut out the triangles that will fill in the sides?  My quilt software is simply evil when it comes to estimating on-point designs. The finished quilt will be roughly 54 x 73 inches - and the quilt software is telling me that I need to buy....

.... oh get ready for this...

...6.5 yards of fabric (42 inches wide).


RIDICULOUS!

I think 1.5 yards should be more than enough.  I do like the cutting instructions the software gives, however, and expect the measurements the software gives me for the individual pieces should be OK.

I've got plenty of left over jelly roll strips to make a couple of nice borders and the binding, but I'm off to the fabric store to get what I need for those triangles to fill in the log cabins.