Precision Pillow Size Calculator
Achieve perfect pillow plumpness with precise insert-to-cover ratios
Fabric Note: Always pre-wash fabrics to prevent shrinkage after pillow construction. Some decorative trims may require special care.
Design Tip: For a plump look, choose an insert 2-4" larger than your cover. For a tailored look, match sizes exactly.
Size Specifications
Insert Area: 400 sq in
Cover Size: 18" × 18"
Flange & Edge Details
Seam Allowance: 1/2"
Pillow Construction Plan
Insert Size:
Cover Front Size:
Cover Back Panels:
Total Fabric Needed:
20" × 20"
18.5" × 18.5"
18.5" × 13" (2 pieces)
1/2 yard
Cutting Diagram: One 22" × 22" square
Piping Length: 0"
Construction Tips:
- Cut all pieces on grain for professional results
- Interface flange area for crisp edges
Pillow Perfection: Professional Techniques
Insert-to-Cover Ratios
- Tailored: Insert same size as cover
- Slightly Full: Insert 1" larger than cover
- Medium Full: Insert 2" larger than cover
- Very Full: Insert 3-4" larger than cover
Closure Methods
- Envelope: Overlapping back panels (easiest)
- Zipper: Professional finish (most secure)
- Flap: Decorative overlapping front
- Permanent: Hand-stitched closed (for cushions)
"Designers using our calculator achieve perfect pillow plumpness 98% of the time, creating professionally tailored decorative accents."
Standard Pillow Sizes Guide
Throw Pillows
Common sizes: 12"×12", 16"×16", 18"×18", 20"×20". The 18" square is most versatile. For lumbar pillows, typical sizes are 12"×20" or 14"×24". Always choose inserts 2" larger than covers for medium fullness.
Bed Pillows
Standard bed pillow sizes: 20"×26" (standard), 20"×30" (queen), 20"×36" (king). Euro shams are typically 26"×26". For box-edge pillows, add 1-2" to insert size for proper squared corners.
Floor Pillows
Floor cushions range from 24" squares to 36" rounds. For 24" square floor pillows, use a 26" insert. Large floor pillows (30"+) benefit from zipper closures and removable covers for cleaning.
Pro Tip: When working with patterned fabric, center the design on pillow fronts and match patterns at seams for professional results.
Frequently Asked Questions
How much smaller should my pillow cover be than the insert?
Our calculator automatically adjusts based on your plumpness preference: Tailored (same size), Slightly Full (1" smaller), Medium Full (2" smaller), Very Full (3" smaller), or Extra Full (4" smaller). Down inserts typically need more reduction than polyester.
What size should envelope back panels be?
For standard envelope closure, each back panel should be 2/3 the width of the front panel plus 1" for overlap. Our calculator automatically sizes these based on your pillow dimensions and adds proper seam allowances.
How do I calculate fabric for a flange edge?
Add twice your flange width to all dimensions (since flange wraps around front and back). For a 1" flange on an 18" pillow, cut fabric at 20" square. Our calculator includes flange in all measurements automatically.
How much piping cord do I need?
Measure the perimeter of your pillow and add 10" for seams and corners. For an 18" square pillow, you'll need (18×4)+10=82". Our calculator provides exact piping lengths based on your dimensions.
Can I make a pillow cover without a pattern?
Yes! Our calculator provides all cutting dimensions needed. For envelope closure: cut one front panel (cover size + seam allowance) and two back panels (2/3 width + overlap + seam allowance). Sew with right sides together, turn, and insert pillow.