For a full and professional appearance, it is standard practice to by 1–2 inches.
Generally, these should use an insert of the same size as the cover to avoid overstuffing and discomfort. Choosing the Right Fill Material how to buy pillow inserts
The primary secret to a high-end, designer-look throw pillow is choosing an insert that is slightly larger than the cover to ensure it remains plump and well-structured. The Golden Rule of Sizing For a full and professional appearance, it is