Dear Khloe,
There are grasslands on every continent except Antarctica, and they cover 20 - 40% of the planet's land area, depending on how they are defined.

Not counting farmland, about 3% of Earth's surface is covered by grassland (or about 11% of Earth's land surface, since 70% of Earth's surface is covered by ocean). However, this excludes farmland, and all of our grain crops (wheat, corn, rice, etc.) are grasses, so in a sense, you could call many farmlands grasslands as well. Farmlands account for about 8% of Earth's total surface, or about 25% of the land surface.