What is the outside measurement of an acre?

Answer 1

An acre is 43560 square feet so any value greater than 740 feet.

That perimeter is attained by a circle.

But the outside measurement depends on how thin and long the area is:

For example,

a 100 ft wide x 435.6 ft plot would have a perimeter of 1071.2 ft

a 10 ft wide x 4356 ft plot would have a perimeter of 8732 ft

a 1 ft wide x 43560 ft plot would have a perimeter of 87122 ft

a 0.1 ft wide x 435600 ft plot would have a perimeter of 871200.2 ft

There is virtually no limit to how thin and long the plot can be and so no limit to how large the perimeter can be.