Not sure what size you need the wall hanging to be but for a 26 1/2 by 24 1/2 you would use 2 1/2 inch squares to replace the 1 1/2 inch squares. For the second measurement just double the whole number and keep the 1/2 inch, for example if the original says 3 1/2 inches you would need 6 1/2, etc. You could then add a border or two if you need it larger. Hope that helps.