The fabric you get should be labeled for upholstery. Then, you have to figure out if it's for light use or heavy use.

If you expect the chair to be used daily, go for the heavy weight upholstery fabric. Otherwise it won't hold up.

If it's for a section that won't see a lot of use, like the back of a chair or rarely sat in, you can go for the medium weight fabric.

One problem with some light weight fabrics is that they stretch quite a bit. Pulling the fabric tight while upholstering could create wrinkles or pull it out of shape and mar the finished product.

For my first 3 upholstery projects, I purchased online from Mary Jo's Cloth Store. I purchased a herringbone upholstery fabric called Jumper and it comes in many colors. I used it for an office chair and a sofa & love seat. I would have used Mary Jo's for my other projects but they did not carry the fabric I wanted to use for those. You can pick on the "Upholstery" link on their web site (see link below) and then browse through all of their fabrics.
They don't sell swatches, but I purchased 1/4 yard amounts of different Jumper fabric colors before making a decision.

You can also email most fabric companies when you see a fabric you like and want to know the "abrasion factor" or number of "double rubs" for a particular fabric you are interested in.

Here is a link that might be useful: Mary Jo's Cloth Store

Many online fabric store show the 'number of rubs' a fabric will handle, with 15,000 being classified as heavy duty. I have linked an article below. It's not necessarily the 'weight' that determines the wear-ability.

Here is a link that might be useful: Fabric Wearability Code How to Tell if a Fabric is Strong Enough

Thanks, everybody!

These chairs will see heavy use, and I don't want to re-do.

(However, at $7/yard, I could reupholster AND make slipcovers, though I'd have to pay for slipcovers)

The site says:
"This high end woven upholstery weight fabric is suited for uses requiring a more durable designer fabric. Uses include any upholstery project, sofas, chairs, dining chairs, pillows, certain types of window treatments, handbags and craft projects."

I'm really hooked on this fabric, but I think I'm going to need to keep looking.

Here is a link that might be useful: Hamilton Montparnase

In case anybody's interested, here's what my final decision was.

I actually found this very fabric at a store here in NYC, for $35/yd. I didn't get a "double rubs" rating, but it was comparable to all the others in weight (the one I had a remnant of is *very* thick).

I also got the suggestion from the woman there that I use my remnant for the center sections of the chairs and find a coordinating one to use for the outer shell. I thought that was brilliant, and went looking. (but I wasn't actually sure I'd have enough remnants to do the interiors both chairs. I think I have enough for the wing chair.)

But I decided that if i bought the 2nd fabric at $35/yard (estimate just under half the fabric, I'd still be spending more ($189) than if I bought the online fabric I really liked at $6/yard. I could even buy extra and have a second seat cushion made, and extra arm covers. And have some extra in case one section got really worn and I wanted to see about slip-covering the upper section only. (true, there could be some fading, but I figure I'll deal w/ that when I get to it.

So that's what I did--I ordered 5 extra yards, and I'll have him make extra seat cushions and extra arm covers.

Thanks for this update. Don't forget to post before & after pics when done : )