The traditional way to estimate fabric needed is:
Measure each piece and color for that piece. Convert to square inches and then uiltiply by number of blocks.
Or - Looking at your picture, there are 196 blocks - 15 x16.
If each block finishes at 5" then add a couple inches for seams. This makes 7" 7x7= 49 square inches in each block
49"x 240 (number of blocks) = 11,760 squares inches Divide this by 1512 (square inches in a yd of fabric 42".
11,760 divided by 1512 = 7.7 total yards - Make it 8 yds.
If there are 3 colors of about equal amount then 8 divided by 3 = 2.66 yds (2 3/4) of each color.
Do the same for sashing and border.
Does this make any sense?