Help with yardage
 

I am getting ready to make a twin size quilt for a friend's little girl. She wants an Easy Cathedral Window Quilt like Jenny Doan of Missouri Star Quilt Company illustrated in her tutorial:
https://www.youtube.com/watch?v=akKU0zg-qaw
The windows will all be pale pink with sides pale green and of course white around the pink centers. My problem is the pattern I bought from MSQC is for a table runner. I have no idea how to figure out the yardage needed for a twin bed. Can anyone help me?

what are the finished dimensions of the table runner pattern?
What are the dimensions of the quilt you want to make? "Twin" is not enough info because you can have a 2 inch drop or a 14 inch drop. Pillow tuck, no pillow tuck etc. so in order to help you with the calculation, we need some numbers.

Either follow PaperPrincess's advice or figure out what size the block is on the table runner then decide how many blocks you will need for your quilt. If the table runner uses 3 12" blocks and your quilt will need 30 12" blocks, just multiply their fabric recommendations by 10. You can use your borders to enlarge the quilt from there.

The table runner is 26x18. I think I'll make it this weekend. That way I'll know exactly how large the block is and will figure it from there. If I'm still puzzled, I'll post again the first of the week. Thanks.

As an estimate, I would say you need 10x as much fabric. If you make a quilt two table runners wide (52") and 5 table runners long (90") it will be a good size for a twin bed.