Having successfully finished the little Rainbow Magic 1/2 square triangle quilt, I've braced myself and begun a full sized project.
I've whipped out the notebook, calculator and my collection of Hope Valley fat quarter fabrics and after several calculations and permutations I decided on 5" squares....the same as charm squares. I debated about 6" which gives a convenient cut out of the 18" side of the fat quarter but I don't know....it just seemed too big for what I want to make. (And I can always use the off-cuts in something else!)
The combo is the full suite of Hope Valley (24 colours) and Kona Solid Ash. Quite vintage and already yielding a few 'ooh's and ahhs' from certain members of the family!