How to Measure for Throw Pillow Covers? | Get the Right Fit

Getting the right fit for a throw pillow cover comes down to one number. Measure the cover wrong and your insert will either slump inside a baggy case or strain the seams of one that is too small.

Whether you are replacing a worn cover or sewing your own, knowing how to measure for throw pillow covers is the difference between a plump, polished look and a flat, sagging one.

The Correct Way to Measure a Throw Pillow Cover

The most accurate measurement comes from the cover itself, not the insert. Remove the insert if you can, turn the cover inside out, and lay it flat on a table or the floor.

Using a soft, flexible sewing tape measure, measure from interior seam to interior seam across the midpoints. Do this for both the width and the height.

• Remove the insert so the fabric lies completely flat without any fullness.
• Turn the cover inside out so the seams are exposed and accessible.
• Measure from seam to seam at the midpoint of each side, not at the corners.
• Record both dimensions — width and height — to get the finished size.

Use a soft tape measure rather than a rigid ruler. A flexible tape follows the fabric and gives you a true reading, while a stiff ruler can bow the material and distort the number.

Why Measuring Inside Out Matters

The finished size of a cover is defined by its interior measurements, taken at the seams, not by the outside edge. When a cover is sewn, the seam allowance folds inward, so the visible exterior runs slightly larger than the actual interior capacity.

Fabric thickness and stuffing also make the exterior look bigger than the true cover size. Measuring the interior seams removes that distortion and gives you the number that actually matters for insert sizing.

This is a solid fallback, but the interior seam-to-seam method is always the first choice when the cover can be opened.

Choosing the Right Insert Size

The extra size fills out the corners and gives the pillow that full, finished look.

When in doubt, check the cover’s true finished dimensions first and work up from there. Guessing insert size without measuring the cover is the fastest way to end up with a limp or overstuffed pillow.

Common Measuring Mistakes to Avoid

If you are shopping for new covers, curated 18 x 18 throw pillow cover options can help you compare styles once you have your measurements locked in.