What size was the Marilyn Diptych painting?

The Marilyn Diptych by Andy Warhol is actually a diptych, meaning it consists of two separate canvases. Each canvas is 40 inches wide by 40 inches high (101.6 cm x 101.6 cm).

So, the overall size of the Marilyn Diptych is 80 inches wide by 40 inches high (203.2 cm x 101.6 cm).