How many kilometers does one degree of longitude approximately measure at the equator?

One degree of longitude approximately measures 111 kilometers at the equator due to the relationship between Earth's circumference and its division into degrees. The Earth is roughly a sphere, and since it is divided into 360 degrees of longitude, you can calculate the distance of one degree at the equator by using the formula: the Earth's circumference divided by the number of degrees.

At the equator, the circumference of the Earth is about 40,075 kilometers. When you divide this by 360 degrees, you arrive at a value of approximately 111 kilometers per degree. This value is valid at the equator where the distance between lines of longitude is the greatest, as they converge towards the poles.

As you move away from the equator toward the poles, the distance represented by each degree of longitude decreases because the lines of longitude converge. Hence, while 111 kilometers is accurate at the equator, this distance decreases as one travels north or south. This is fundamental for understanding geographic coordinates and navigation, emphasizing the significance of the equator in geographic measurements.