I would use this calculator and make sure to round up to account for inside seams if they are not included in the block information you have. All you would have to do is figure the percentage of each fabric in the block (that's just the total for each separate fabric divided by the total of all fabrics in the block).
http://www.hickoryhillquilts.com/fabric-calculator.htm Borders, sashings, binding, cornerstones, backing, etc would have to be figured separately.