No other film in Britain has ever taken more than £10m in its first weekend, nor sold so many tickets on a Saturday.
Some £4m of tickets were sold on Saturday, beating the record set by the Philosopher's Stone in 2001.
And adding in all the money the preview screenings made too, the second Potter film has made a whopping £18.9m in Britain according to Warner Bros.
COS didn't set a US box office record, but did make history in another way.
It was shown on 8,515 screens in 3,682 US cinemas, the widest opening release ever for a film.