Does the quilt lay flat??? If it does than you measure from the middle from top to bottom and then do the sides from top to bottom. I usually take the average of the three measurements for length. Now do the same with the width if thee measurements are not way off you will be alright. You cut the binding to the length and you will ease it to the quilt pinning and matching the center of quilt and center of binding. Do both sides then you will co the binding on the sides hope this helps you