What color is the TARDIS exterior?

The TARDIS exterior is blue. More precisely, the Doctor’s TARDIS usually appears as a blue British police box, an instantly recognisable disguise that became one of Doctor Who’s defining visual symbols.

TARDIS stands for “Time And Relative Dimension In Space.” Although it is vastly larger inside than outside, its exterior has generally remained in the form of a police telephone box since the programme began in 1963. The design was practical as well as imaginative: police boxes were familiar street fixtures in mid-20th-century Britain and offered an inexpensive, distinctive shape for the Doctor’s time machine.

The exact shade of blue and several exterior details have changed across different Doctors and production eras. The roof, windows, door signs and St John Ambulance emblem have all varied. Those changes do not alter the standard quiz answer: the Doctor’s TARDIS is the blue police box.