Quilt backing calculator
Questions
How much backing do I need for a throw quilt?
A 50" × 60" throw needs a backing of about 58" × 68". From 42" fabric that is two 58" lengths joined with a horizontal seam, about 3¼ yards, or 2 yards of 108" wide backing.
Should the seam run vertically or horizontally?
Either works. The calculator checks both directions and chooses whichever needs less fabric; horizontal seams are often cheaper for wide quilts.
Is wide backing worth it?
For quilts wider than about 72", 108" wide backing avoids seams entirely and often costs about the same as pieced yardage.