Pillow Cover Size Calculator
Get exact cutting dimensions for any pillow insert size and closure style.
Results are estimates. Always add extra for shrinkage, mistakes, and pattern matching.
How to Use the Pillow Cover Size Calculator
Select your pillow insert size from the dropdown or enter a custom size. Choose your preferred seam allowance. The calculator will show cutting dimensions for three closure types:
- Envelope Closure: Two overlapping back pieces — no zipper needed. Quick and easy to remove for washing.
- Zippered Cover: Clean finish with an invisible zipper. Front and back panels cut to the same size with zipper allowance built in.
- Simple Sewn: Two identical panels sewn together. Stuff the insert then hand-stitch or slip-stitch to close.
Common Pillow Insert Sizes Reference
| Insert Size | Front Cut | Env. Back (each) | Zip Front/Back |
|---|---|---|---|
| 14" sq | 15" × 15" | 15" × 10.5" | 15" × 15" |
| 16" sq | 17" × 17" | 17" × 11.5" | 17" × 17" |
| 18" sq | 19" × 19" | 19" × 12.5" | 19" × 19" |
| 20" sq | 21" × 21" | 21" × 13.5" | 21" × 21" |
| 22" sq | 23" × 23" | 23" × 14.5" | 23" × 23" |
| 24" sq | 25" × 25" | 25" × 15.5" | 25" × 25" |
Note: Sizes above use ½" seam allowance. Adjust per your chosen seam allowance.
About this Pillow Cover Size Calculator
This calculates cutting size from your insert size plus your chosen seam allowance — the three closure types (envelope, zippered, simple sewn) all start from the same front-panel math but differ in how the back is cut and finished, which is why all three appear together instead of as separate tools.
This assumes a cover cut to the exact insert size
Some sewists cut the cover exactly to the insert size plus seam allowance for a snug, structured look; others cut it 1–2" smaller than the insert on purpose for a fuller, more stuffed appearance. This isn't a universal rule either way — this calculator assumes an exact match to the stated insert size, so size the cutting numbers down yourself if you prefer the fuller look. See the Seam Allowance Calculator if you want to compare a different allowance than the presets here.