There fabric calculators on the web free..but when I do something like that..I increase the material the pattern calls for by how many extra rows..if say the blue color for the border for 3 rows is one yard..and I want 3 more border rows just like the pattern roll..I buy another yard..I am one of these people who hardly ever finish a pattern the way it is lay out..I usually always go bigger..or if I am not completely sure..I buy more..I love scrape quilts so this works for me...