I am making a quilt that was supposed to be queen size but the recipient got a king size bed. I am adding some borders. My question is: how big is too big for the outer border. I am thinking finished at 8" to 10". Do you think that will be too wide?

If it fits the bed it is not too wide :-).

I had the same problem when my son and dil got a queen and I was making for a double! I simply added more borders, one smaller one and one larger. Your 8-10 inch one should be Ok on a king size bed. How big are your blocks? Usually that governs how big my borders are. Your large border might be better as 2 smaller, say a 4 and a 6 inch OR a 3 and a 7. Clear as mud?

There is a 1 1/2" inner border, then a 3 1/2" border (the original outer border, then I added a 3" border and now this one. If I make this one finished at 10" I will have added 13" per side which would be total 26" length and width. If finished at 8 " then added 22". Hopefully that is enough. I have backing and batting for a king, so I am ok there. So will 10" be too much?

If it looks good to you than it will be OK.

Do you have a pic?

It is made from strips and has a diamond pattern so the blocks won't be noticeable as such. They are made from 8 by 6 1/2 rectangles cut diagonally and sew triangles together. When you look at the quilt you see lines making up the diamond as opposed to separate blocks.

well I think you can do whatever you want, as long as it works for you. i am going to be making a quilt from the back to nature line and there is a stripe that is 11" wide. I'm going to use it for my border. i certainly didn't want to split the design. i think most everybody would be focussed on the top anyway,

The last border on our round robin quilt is 8" - so you should be OK.

Well, I may be in the minority. I'm not a big fan of really big borders. To me they look like an afterthought just to make the quilt big enough.

I prefer three even borders (like 4" each), or a wide, a thinand a wide. maybe 5", 2" and 5", look much more planned and frame the quilt well.

there is always a pieced border you could put in there too so you wouldn't have a really big one.