A tiny (8.869 millimeters / 0.349 inch) radius sphere representing the volume Earth would have to be compressed in order to form a black hole.
An alternative version of this object, with an "Earth like" texture is available here.
For non-rotating black holes the Schwarzschild Radius also represents the distance from the singularity to the event horizon, so put otherwise, this globe also represents the "size" of Earth's (or a mass similar to Earth's) black hole, size in this case meaning the radius of the sphere after which an object falling towards the center of the black hole cannot escape.(escape velocty > light speed)
It is worth noting that were Earth suddenly replaced by this black hole the Moon, or even the ISS would continue orbiting around it as normal, since black holes merely have the mass of their parent object and don't actively "hoover" space around them.