I need a new seatback cushion for an armchair--any thoughts?

That sounds like a standard pillow size…

Why not just find a pillow case you like and put a standard pillow in it, then stitch witch the opening (or just fold it and tack sew it.

If you want to get fancier you could get a ½ yard of upholstery fabric to match the chair & use that iron on tape to adhere it to the front side of the pillow case.

A standard pillow is only about 15 by 20 or 25 inches, I need one that’s quite a bit bigger. (about 20×30 or more)

Then use a King size. But, you’ll have to cut it down to 30”...it’s still cheaper to head to Kohl’s or Wal-mart, get a pillow & pillow case & make it work.

You can find foam pieces at an upholstery store and cover it. It doesn’t take long and you can make the cushion whichever size you want!

They will even cut it for you!

Depending upon where you live, you could go to a place that sells foam mattresses and foam cut to fit. Check the yellow pages.

Most of their customers are businesses but the also sell to the general public on a walk in basis.

This way you can get it cut to fit and stitch witch cover it with any fabric you want.

They are usually pretty dirt cheap.

Standards are about 18×24

Kings are around 20×30 to 20×36

I’ve done this project a few times…I find using a pillow the easiest, and most comfortable to sit with…Now, if it were for the base (seat part) I’d recommend foam.

That, too is easy and fairly cheap.

@Buttonstc: Cool, so, what keyword should I look for in the yellow pages?

You could go to the fabric store and buy square cushion foam and cut it to that size. Without sewing, you can still create a cover for it. Select fabric that will match or compliment and cut two squares (or rectangles since your cushion is a rectangle I guess)- one for the front panel of the cover, and one for the back. Make sure the panels are several inches larger than the foam or pillow. Simply sandwich the foam between the front and back panels and tie the fabric together at each corner in a knot. You could even tie ribbon around them to decorate, but the fabric knots are sometimes cool looking on their own. If you don’t like the tied off look, you can tie them together so that the pieces are inside-out, then flip it right-side-in and smoosh the pillow inside last since all the sides are open. You can tuck in the edges between the knots to make it look neater. If the ties aren’t holding, you can pin them.

I’m trying to find a picture or tutorial and am not having luck. I saw it on a decorating show years ago. I’ll keep looking.

@ubersiren: Wow, that sounds really easy! So, at a place like Jo-Ann, they would have “cushion foam”? Or a different kind of store?
(edited because their website had a bug.)

@La_chica_gomela : Yeah, it’s probably in back by the quilting or upholstery stuff. There are many types of foam, but when you go back, you’ll see what I mean. You can get a “slab” of foam, and someone will cut it to the size you need in the store. You can double up if it’s not as thick as you need, or cut it down if it’s too thick. Ask someone there to help you if you need it- they’re usually very willing to help.

If the fabric you get is too thick to tie, you can always punch a hole in the corners and tie it together with some ribbon or some decorative thing like that…

Several great ideas already – here’s what I did. I bought a complete, foam-backed fitted chair cover. Then I bought a foam padding, and cut to fit the chair. I glued the foam padding to the chair, and then covered it with the fitted chair cover.