How do you do square feet of outdoor carpet with holes in it?

Find the length and width of the carpet, and multiply the two numbers together. Depending on the size of the holes, you can just round the square footage to what you came up with before. If the holes are significantly sized, measure from one side of the hole to the other to find the holes diameter. Divide the diameter in half to find the radius, and square it. (To square it is multiplying it by itself.) Multiply the radius squared by 3.14. Repeat this on every hole, and subtract it from the square footage of the blanket if it didn't have the holes.