That depends on what you mean by "big"! Here are some different ways to measure the size of Earth:

Circumference:

* Equatorial circumference: 40,075 kilometers (24,901 miles)

* Polar circumference: 40,008 kilometers (24,860 miles)

Diameter:

* Equatorial diameter: 12,756 kilometers (7,926 miles)

* Polar diameter: 12,714 kilometers (7,900 miles)

Surface area: 510.1 million square kilometers (196.9 million square miles)

Volume: 1.08321×10^12 cubic kilometers (2.59876×10^11 cubic miles)

Mass: 5.97237×10^24 kilograms (1.317×10^25 pounds)

Fun fact: Earth is slightly flattened at the poles and bulging at the equator, making it an "oblate spheroid". This is due to its rotation.