QuiltTally / Guide
Usable fabric width and quilt yardage allowances
Measure useful fabric width, separate seam loss from overhang and understand why rounded yardage is not a complete cutting guarantee.
Usable width is what remains for the project
Measure between the edges you can actually use after excluding selvedges and other unusable areas. A nominal roll width is not necessarily the same measurement. Check your specific fabric rather than applying one fixed deduction to every product.
Separate three different allowances
Overhang increases the target backing size around the quilt. Joining allowance reduces the width of panels after seams are sewn. Purchase rounding increases the amount bought to a chosen increment. Each affects a different part of the calculation; none silently covers all the others.
A small width change can add a panel
A backing just wider than two panels can suddenly require three. At 42 inches usable width and ½-inch allowances, two panels provide 83 inches. At 41 inches, they provide 81. That two-inch difference may cross your target and change the buying plan substantially.
Add project-specific extras deliberately
Prewashing and shrinkage, straightening the grain, pattern repeats, damaged edges and matching motifs can consume fabric. Decide those allowances for the particular material and design. A rounded purchase is not a guarantee that an exact pattern match will fit.
Keep a record with the fabric
Print the entered width, seam allowance, target dimensions and chosen orientation. If you later change fabrics or ask someone else to quilt the top, that record explains how the number was obtained. Recalculate when a key measurement changes rather than relying on the old yardage.
Questions, answered
Can I enter centimetres?
These quilting tools currently use inches for dimensions and yards for purchase quantities. Convert first and keep the units consistent.
Should I measure before or after prewashing?
Use the dimensions appropriate to how you will cut and use the fabric. If shrinkage is still expected, allow for it separately.