Hubble Science Image Utilized in "Touch the Universe" - Uranus
The semi-major axis of Uranus's orbit about the Sun is 19.18 astronomical units or roughly 1.8 billion miles (2.9 billion km).
The planet has a diameter of roughly 32,000 miles (26,000 km) at the equator.
NASA and Erich Karkoschka (University of Arizona)
Image from PRC1998-35, "Hubble Finds Many Bright Colors on Uranus"