Formulas
Compare finished size to the quilt & mattress chart. width = blocksAcross×block + (blocksAcross−1)×sashing + 2×border (same for length). Fit mode floors how many block+sashing steps fit inside the target after borders.
Worked example
8×10 grid of 12" blocks with 2" sashing and 4" borders produces a large top—use the tool to tune block count before buying fabric.
Standard sizes
Baby ~36×52", throw ~50×65", twin ~64×86", queen ~84×92", king ~100×92" on many quilt-shop charts. Mattress sizes differ; add drop for bedspreads.
Tips
Finished block size is after seams. Measure a sample block before committing to yardage.
Common mistakes
Mixing unfinished and finished block sizes; planning backing before final borders.
Mattress and drop planning
US mattress sizes commonly include twin 38×75", full 54×75", queen 60×80", king 76×80", and California king 72×84". For a pillow-tuck quilt, add length; for a draping coverlet, add drop on sides and foot. Compare your finished top to mattress + drop before cutting borders. Keep a notebook of block unfinished vs finished sizes for recurring patterns.
Limits and how to use the results
Estimates run only in your browser. Prefer a published pattern’s tested yardage when it conflicts with this planner. Density factors and assumptions are documented on the methodology page; legal terms cover planning-use limits.
FAQ
What size is a queen quilt?
Many patterns use about 84×92" for a queen top; confirm mattress plus desired drop.
How many 12" blocks for a twin?
Often around 6×8 to 7×9 blocks depending on sashing and borders—use fit mode.