When I measure for my binding I always add 10" at least to the measurement so I have some to fiddle with when I come to the two ends. I add my binding at the ironing board using Elmer's Glue before I take it to the sewing machine so no straight pins to prick me and get blood on my close to finish quilt. I usually make up my binding before my quilt is even completely by cutting the strips needed. I estimate what the quilt top is supposed to end up at in size and then give myself an extra strip just for safety measure. Those extra strips will go into my scrap box for the same size so nothing goes to waste here.