jelly rolls
 

what shape quilt would I get if I used two jelly rolls ..I need a bigger quilt than I get with one jelly roll??

You could have an almost infinite number of shapes, depending on how you stitched your 80 strips of 2.5" x 42" fabric. Not sure I understand your question.

There are different amounts of pre-cuts depending on the brand, and it depends whether you are seaming them on the short edge or the long edge.
RK rainbow jelly roll has 41 strips that are 44" long. If you pieced only on the long side, your quilt would be 43x164" on the short side would be 86x82". Of course you could always choose to add 2 more strips or crop the edges if you want it perfectly square (actually the strips are not always identical widths anyways so there would likely be cropping regardless).

Are you talking about doing a Jelly Roll race quilt? Where you sew all the strips end to end. Then line up the two ends and sew them together, snipping when you get to the end. Repeat until you get the shape you want.

If you go to the website www.jellyrollfabric.net and sign up, you can download her free e-book on using jelllyrolls. It has a great pdf file for sizing jellyroll quilts. I recommend reading the whole file.

Plus she has great selection and sales on her jelly rolls. She only has 20 strips to a roll tho, so you will have to figure out how many rolls you need for what you want to do. I also like that her rolls are not pinked, just straight cut edge.

I am planning to make an Island Chain quilt and it only needs one jelly roll. Quilt will be a lap size.

This is really a mathematical question. Assuming you have 40 2.5" strips in each roll.
You will have a quilt either 106 wide by 64 long, or 53 wide by 128 long.

When you do a jelly roll race you are continuously dividing the loooooong strip in half. If you start out with 2 jelly rolls it is approximately 3440 inches long.
You sew it in half once, 1720 x 4.5
Sew in half 2 times, 860 x 8.5
3 times, 430 x 16.5
4 times 215 x 32.5
5 times 107.5 x 64.5 (this is where you normally stop - jelly roll race sewn with .25" seams is 64.5" long)
If you go for one more 53.75 x 128.5

If you want a longer quilt, but still sort of square, you have to use wider strips.
I think I once used 45 - 3" strips to get a quilt 80" long and 60" wide.

Understand, I am a math person and love to figure these things out!!!
Good luck!
Ann

Thank you for the link. Cool website.