I bought long ago the book: [u]The Quilter's Pocket Reference: an Easy guide to Yardage and More[/] by Peggy Scholley. It has excellent reduction/enlargement charts. I know they are sold online used or new. Most LQS's have these. This is one of my Bibles for Quilting. I keep my other notes tucked in mine for future use.
There are plenty of net based online conversion charts available to either decrease or increase size. Give it a browse. You can also buy those round guides that many LQS's sell that help you with resizing. Sorry, can't remember what they are called.
ali