The Färentuna runestones are 11th century runestones labelled U 20, U 21, and U 22 in the Rundata catalog that are located in Färentuna, Uppland, Sweden. Runestones U 20 and U 21 were registered separately although they come from the same original runestone and consequently are called U 20/21. The runestone U 20/U 21 is probably most interesting as it, together with the Hillersjö stone and the Snottsta and Vreta stones, tells the story of the family of Gerlög and Inga.