It's no secret I love throw pillows. I think most interior enthusiasts do! They can be the pièce de résistance that makes a room feel finished, as well as easily switched out to change the whole feeling of the space.
As a former interior designer + several years experience running an industry fabric showroom under my belt I'm quite familiar with pillow talk. If you're thinking about purchasing or DIY-ing pillows for the change of seasons, you may want to check out the guidelines below to make sure they look their best!
Feather & Down - Down fills are typically best as they're all around loftier, and can be fluffed overtime to maintain their shape and volume. Tip: The more down content there is in the feather/down ratio, the better!
Synthetic Spun Polyester - Think craft store inserts. Synthetic fiberfill is generally a lesser quality insert as they flatten, lose their shape, and become lumpy overtime. I almost never use them, except for in these tufted pillows! In this case, the synthetic insert stayed in place and proportional in the pillow better than down would have.
Down Alternative - Though down alternative is technically still polyester fill, its composition is such that it mimics down's lofty clusters, making it a great down stand-in for anyone with down allergies. Crate & Barrel has a good down alternative pillow option.
Outdoor - Usually filled with water & mildew resistant acrylic or polyester fibers to hold up to the elements.
Typically we see ready-made pillows in stores at 18″ squares, but it's no secret designers hate wimpy pillows which is why they often have them made custom. If you're up to the task of sewing your own pillows, you might want to consider opting for 20″-22″ size, as it's a bit more of a luxe designer look. My personal size preference is 22″ square. Some designers even go up to 24″ squares depending on the size of the sofa or chair.
Square pillows are probably the most common shape, but there are tons of other shapes out there too: lumbar, circle, bolster, etc. Don't be afraid to mix and match sizes and shapes like Amber Lewis of Amber Interiors has done in the space above.
In terms of pillow insert sizing, the general rule of thumb is to use inserts that are 1″-2″ larger than your pillow cover. (I usually go 2″ larger.) So for example, with a 22″ square cover, use a 24″ square insert. Going a step larger with the insert makes for a more voluminous, high end look.