# Calculate the Diameter of earth using Latitude lines

I have a basic question : Earth has 181 latitude lines, each having distance of 111 km. if i multiply that i will get 20091 KM, which could be the sum of distance from north pole to south pole i.e Diameter of earth, but the original diameter of earth is 12742 km, where does the 8000 Km value goes?

• Ummm, 180 latitude lines and you mean the distance at the equator and that gives you the half-circumference, not the diameter. This question should probably be closed, sorry. – user967 Dec 10 '16 at 20:24
• As Barry said, you are calculating the length of the half-circle over the earths' surface, not the diameter through the earth. – Jan Doggen Dec 10 '16 at 22:41
• @Barry A minor quibble: 180 gaps between whole degrees of latitude, but only 179 latitude "lines" ( well circles really) -- the poles are points only. – Spencer Dec 12 '16 at 20:13

The circumference of a circle is given by ${\pi}d$, where $d$ is the diameter. Divide 40 000 km by $\pi$ & the diameter of the earth is 12 733 km