Is the Earth's equatorial circumference the same as the polar circumference?

No. The polar circumference of the Earth is smaller than the equatorial circumference by about 41 miles or about 67 km.

The Earth is a slightly "oblate spheroid" meaning it is slightly flattened (0.336%) at the poles, and bulging at the equator, due to its spin.

The equatorial circumference of the Earth is about 40,075 kilometers (24,901 miles).

The polar circumference of the Earth is about 40,008 kilometers (24,860 miles).

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