I want to make a king size 10 minute block using 8" block just 2 colors. Can someone tell me how much fabric I will need.

Are you wanting to know how much material for the 8" block?
I make a 12 1/2" block and use( 5) 6 1/2" squares. 2 of one color and 3 of another. So if you want an 8" finished block, use 4 1/2" squares, 2 of one color and 3 of the other. However, the smaller the squares, the harder it is to do the middle square.

I also tried (4) 6 1/2" squares and the center square was 12 1/2" square. Once you figure out how much material you need for each block, then multply that times the # of blocks you need.

I was planning on using 8" blocks the same color with a different center block.

Then cut (4) 4 1/2" squares of one color and (1) 4 1/2" square of the other for 1 block. Tell me the finished size of the quilt you want and I will see if I can figure it out. I have a quilt calculator to help figure the yardage. I am new at this, but I will try for you. Figure out how many blocks you want for width and how many for length, or the finished size of length and width. Have you made a 10 minute block using the finished size as 8"? I know making the 12 1/2" block with the 6 1/2" center is difficult enough. It would be difficult to make the 4 1/2" center. Try one block and see how it is for you.

No that is not what I mean. I want to cut 4 8" blocks of one color and one for the center another color. I want to make a king size quilt. Any help would be appreciated.

Your finished block size will be 15 1/2". You need to decide what the total length and width of the quilt will be. There are different sizes for king size quilts. Do you want a coverlet? How far do you want it to drop on each side? When you figure out the size that you want, it will be easier to figure the amount of material.