Question

What is Earth's spatial surface?

Answer 1

Total surface area of earth: 510,072,000 sq km

Total water surface area: 70.8% (361,132,000 sq km)
Total land surface area: 29.2% (148,940,000 sq km)

Ref: http://chartsbin.com/view/wwu

Explanation:

According to modern estimates, the surface area of the Earth is approximately 510 million square km `(5.1 x 10^8 km^2)` or 196,900,000 square miles. Determining this was not only a matter of ascertaining Earth’s dimensions, but also its proper shape.

A nice detailed discussion of the non-spherical model calculations (with graphics) is here:
https://www.universetoday.com/25756/surface-area-of-the-earth/