Measure the bed with its usual bedding
Measure the actual mattress width and length with the sheets, blankets and pillows that will sit underneath the quilt. Decide where the lower edge should finish: just below the mattress, past the bed rail or above the floor. Measure that vertical distance from the mattress top as the drop. Side and foot drops can differ. A tall mattress can need a wider quilt than a thin mattress with the same width; a footboard may limit the length you want.
Turn the measurements into a target
Target width = mattress width + left drop + right drop. Target length = mattress length + foot drop + optional pillow tuck. For an example 60 × 80-inch mattress, two 12-inch side drops and a 12-inch foot drop give 84 × 92 inches without a tuck. A separately chosen 10-inch tuck makes the target 84 × 102 inches. These are design choices for this example, not a required queen quilt size. Use the same unit throughout.
| Example choice | Target width | Target length |
|---|---|---|
| 12-inch side/foot drops; no tuck | 84 in | 92 in |
| Same drops; 10-inch tuck | 84 in | 102 in |
Check the block layout against both dimensions
Open the layout calculator in target mode. With 12-inch finished blocks, no sashing and no borders, 84 × 92 inches requires 7 columns and 8 rows: 56 blocks and an 84 × 96-inch top. For the 84 × 102-inch target, the rows rise to 9, producing 84 × 108 inches. A border or sashing can reach a target with different counts, so compare the whole design before making more blocks. A target is a minimum, not a promise of an exact finished fit.
Allow for the difference between a planned top and a used quilt
The calculated top size is the finished design after seams, before quilting and washing. Stitch density, batting and fabric behavior can reduce the dimensions later. There is no single reliable shrinkage percentage for every project. Test the actual materials or discuss an allowance with your quilter, then choose a larger planning target if needed. Do not add backing overhang to this bed target: backing and batting have their own extra margins beyond the measured top.
References and further reading
Examples and calculations are explained above; follow your pattern and measure your own materials before cutting.