How many square feet are there in one city block?

How many acres in One Chicago City Block ?

It depends on the city. In New York City, the average length of a north-south block is 1/20th of a mile, or 264 feet. An east-west block is about 1/5th of a mile, or 1,056 feet.
So, a square block would be 264 x 1056 = 278,784 square feet, which is equal to 6.4 acres.

Chicago city blocks (if you count each block as 100 in the grid addressing system) are 1/8 mile long so a square mile is 8 blocks x 8 blocks. Since there are 64 square blocks in one square mile and 640 acres in one square mile, we know that Chicago city blocks (e.g. from Ashland to Paulina and Addison to Waveland) would be equal to exactly 10 acres per square block.