Quilt border calculator
Plan up to three straight, butted quilt borders. Get cut widths, assembled lengths and a strip-by-strip crosscut plan, then carry the new top size into backing and binding.
Enter borders from inside to outside
Measure the assembled center through its middle. Enter the visible finished width of each new border. Set unused rows to zero. Borders already attached belong in the center measurement; do not enter them again as planned borders.
The plan attaches left and right first, followed by top and bottom. Each border row is a separate fabric, with its own usable width after selvages. If you use the same fabric in several rows, combine the actual cut lists when ordering rather than treating summed yardage as an optimized layout.
How the cutting plan works
For a current raw top W × H, finished border width b and attachment seam allowance s, cut width is b + 2s. Assemble two side runs of length H, then two top/bottom runs of length W + 2b. The new raw top is W + 2b by H + 2b. Repeat for the next border.
A run longer than the usable fabric width needs joins. Straight joins consume twice the seam allowance; square-overlap diagonal joins consume one strip cut width. Each run is divided into full-width segments and a final segment with its join allowance included. The planner places the largest segments first into available width-of-fabric strips. This creates a feasible cut list, but does not guarantee the least possible yardage or ideal seam placement.
Example: a 48 × 60 in center with one 3 in finished border and ¼ in seams needs 3½ in cut strips. The side runs are 60 in; the top and bottom are 54 in. Using 42 in fabric and straight joins, cut four 42 in pieces, two 18½ in pieces and two 12½ in pieces. They fit into six WOF strips. Cut depth is 21 in, rounded to ⅝ yd when buying in ⅛ yd increments. The new top measures 54 × 66 in.
Before cutting
Use the dimensioned list, not the schematic diagram, to cut fabric. Piece labels identify each assembled edge and its join order. Very short end pieces may put a join too near a corner; consider extra fabric and adjust seam placement. The calculation includes no saw/rotary kerf, repeat matching, shrinkage, mitered corners, bias cuts or lengthwise border strips. Keep the quilt square and measure your actual top before each layer.
Technique reference: Moda’s quilting counter guide (PDF). Our cut list follows the seam geometry displayed above.
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