The Earth's circumference is approximately how many miles?

The Earth's circumference is approximately how many miles?

• A. 24,901 miles
• B. 21,000 miles
• C. 21,600 miles
• D. 18,000 miles

Answer: (C)

Think of Earth’s size in terms of circumference using C = 2πR. The average radius of Earth is about 3,959 miles, so the circumference is roughly 2 × π × 3,959 ≈ 24,900 miles. Because Earth is slightly flattened at the poles, the polar circumference is about 24,860 miles, but the equatorial value is still in the neighborhood of 25,000 miles. So the approximate circumference is about 24,900 miles, not 21,600. The 21,600 mile figure would imply a radius around 3,440 miles, notably smaller than Earth’s actual size, which is why that option doesn’t fit the real measurements.

Think of Earth’s size in terms of circumference using C = 2πR. The average radius of Earth is about 3,959 miles, so the circumference is roughly 2 × π × 3,959 ≈ 24,900 miles. Because Earth is slightly flattened at the poles, the polar circumference is about 24,860 miles, but the equatorial value is still in the neighborhood of 25,000 miles. So the approximate circumference is about 24,900 miles, not 21,600. The 21,600 mile figure would imply a radius around 3,440 miles, notably smaller than Earth’s actual size, which is why that option doesn’t fit the real measurements.