The chancellor said this morning he "didn't recognise" the sums of money being discussed by the EU in relation to Brexit.
Hammond said on the BBC's Andrew Marr Show that no Brexit deal would be "a very, very bad deal", but added that a worse deal would be one in which the UK was "punished" for leaving the EU.
The chancellor also said he "would have liked" to tear apart the economic policies laid out in Labour's manifesto, while spending more time highlighting the Tories' economic record during the campaign.
"In my judgment, we didn't talk about the economy as much as we should have done," Hammond said.
The UK now needs a "period of calm", Hammond said, when asked how long Theresa May will remain as Prime Minister.