you measure across the top, middle and bottom. add those and divide by 3 to get just over 85 1/2. that will be easy to fit if you match centers of quilt and border, pin, pin ends and in between. then sew. good luck!

I agree with Aria. Measure the center and, not the ends, but at the quarters, then average. That measurement will make it easier to ease the border to the quilt. When I pin, I pin at the center, the quarters, and if it is a very large quilt, I will also pin at the eighths. Do this to the border strip also. This helps to manipulate my ease in each section. I also use a bamboo skewer to help hold down the fabric (and it can also help scrub some extra fabric into the ease without puckers). Hope I explained clearly.

I don't know if I dare write this. You can delete it if you wish, but I PULL on both sides of the needle. Yes, I do!
If one side is longer than the other, I put a pin on the seams that need to match (if you don't, the seams can "pop"). Then I put one hand behind the needle and the other in front, and pull apart as it goes under the needle. The fabric still goes where the feed dogs want it to. Just feed as fast as they want it.

On borders that are not quite the same length as the quilt, I put pins at both ends, in the center, and then in several places between ends and center, always finding the center of the space that is left. (I fold it in half to find centers.) Then just a gentle pull as I sew gets it perfect. I can get rid of a lot more than an inch that way and it can't be seen.

How many borders are you adding? 1 inch may not seem like much for only adding 1 border but that inch can "grow" the more borders that you add. I was taught to measure from the center and that is the length of your border. In fact I only measure the center ONCE and use that measurement to cut the borders. I then match centers, 1/4s and ends of border and top and ease in any excess BEFORE I sew. Also put piece that is too large on the bottom next to feed dogs so they will help ease in any excess. You can also gently stretch the bottom fabric to fit but try to do it eavenly. You can also "shrink" the excess part by spraying well with water and let that dry and fabric should shrink a little Again thart 1in does not seem like lot but borders cut WOF will stretch a little so your 1" too big border can become several inches too big by the time you are done. This may seem picky but as a quilter I try to do the best I can which is not usually perfect.

I also, like to add extra on the bourder when I am sewing it. That way if for some reason I have made a miss calculation, the border will still work. Yep, I'm not perfect !!!