# What is the circumference of the earth inches?

6,082,560,000

Circ. of Earth (through poles):

40,008 km

1km = 39,370.0787 inches

40008 * 39370.0787 =

1,575,118,108.6296 inches (1.575 billion) This kind of item can be fun, and calculating the answer can be fun as well. But keep in mind that within the question is a hidden and perhaps even unintended assumption about the accuracy of the expected answer. If you are starting your calculation with a figure estimated to the nearest kilometer, for example, does it really make sense to calculate an answer that looks accurate to the nearest inch? It would also seem needless to take an estimated number of inches only to leave several degrees of magnitude of the estimate unspecified (zero). It is an important aspect of measurement and not a minor point at all. In the sciences and in engineering, measurements should be in reasonable units and should reflect the degree of accuracy that their numbers suggest. Imagine being on a team building a long tunnel under a mountain. Measurements for the two starting points and for the exact directions appear to be accurate to a millionth of a meter, but in reality they are accurate only to the nearest kilometer. What are the chances that the two ends will meet in the middle? Just about zero. The length of Earth's equator is about 40,075.0 km, or 24,901.5 miles. The exact length is 40,075,016.6856 m in WGS-84, and 40,075,035.5351 m in IAU-2000. I got these figures on-line, and I cannot verify their accuracy. But if they are what they appear to be (there's the rub) then calculating inches from this starting point might make sense. On the other hand, you might be curious, as am I, why these two "exact" figures are so different.