This picture shows the sizes of the original three dwarf planets (Eris, Ceres, and Pluto) as compared to Earth. It also shows Pluto's large moon Charon (and its two small moons Nix and Hydra) and Eris's moon Dysnomia to scale. The image also shows Earth's Moon (Luna) and the planet Mars for comparison. None of the distances between objects in this image are to scale.
Images courtesy of NASA, ESA, JPL, and A. Feild (STScI).