the charts i have show a queen quilt as 88"x94"---then you would want to determine how much of an over=hang you want- some of the newer mattresses are 15-16" high= if you want the quilt to drape down the sides past the mattress you need to add for that- a 15" mattress would mean adding 30" to the width (if you wanted it to cover the mattress sides)---best to have someone measure her bed and determine how far down they want it to hang over- and if you want a 'pillow tuck' you need to add in for that too.