is extra backing necessary?
 

Is it necessary to have extra backing when quilting on a domestic sewing machine if I pin well near the edges before beginning quilting? Thanks!

To be on the safe side, it is important to have at least a little extra backing.

It is quite possible that the top and batting shifts during the quilting process so yes, a little extra can save your bacon.

I have always used at least 6" (3" per side, top and bottom"). I hand baste and still get shifting. I have always been glad that I had that little extra, I have always needed at least some of it.

So do you think an inch would be sufficient? or ____ more?
I'll just stitch-in-the-ditch so there wouldn't be the sideways or circular movements that are probably part of FMQ'ing.
Thank you SO much

How much extra you need depends in part on how large the quilt is. An inch extra on each side would likely be sufficient for a lap size quilt or smaller. I would leave two inches on each side for anything larger than that. A lot depends on the level of risk you want to take in terms of running out of space if things shift.

Another thing that affects shifting is the batting you use. Polyester batts are more slippery than cotton or wool and tend to shift more.

Basting method can also affect shifting. I have gotten the least shifting with spray basting; more shifting with pins and thread basting.

Edit: I should add that pinning the edges well will not affect how much the layers shift. If you get to an edge and you run out of batting before you run out of top, it won't matter if the edges are pinned. Pinning the edges simply protects against things such as the backing inadvertently getting folded back while you are quilting.

Edit 2: Actually, running out of batting isn't the worst problem; you can always add a strip of batting to an edge. It's running out of backing or top that creates a bigger issue.

I give myself 3 inches on each side.

in short, yes. It feels like a waste until that one time that you realize why you need it. The extra material is great for scrap quilts. no waste.

YES! Yes! Yes!

Wow, THANK YOU ALL!! You not only answered in detail but also explained why. I greatly appreciate your help.
What a wonderful resource you all are. There's no substitute for so much experience.