Our list below reveals the stance of major papers as the EU race enters its last days, with The Times, Sun, Guardian and Mail on Sunday among those that have also picked a side.
By The Huffington Post UK's estimation, totalling up the print circulation of newspapers which have declared their positions shows papers supporting Leave have an audience of around 4.8 million, while those backing Remain reach just over 3 million.
The University of Loughborough looked at the tone of coverage of the EU Referendum in the papers and claimed that, weighted by circulation, Leave has an 82% to 18% advantage over Remain.
The Sun, Britain's most-read print newspaper, came out for Brexit in mid June, arguing: "We must set ourselves free from dictatorial Brussels.Throughout our 43-year membership of the European Union it has proved increasingly greedy, wasteful, bullying and breathtakingly incompetent in a crisis."
The Daily Mail (print circulation 1.5 million)
The Daily Mail backed Brexit on Wednesday, in opposition to its sister paper the Mail on Sunday. According to Loughborough University, the mid-market paper is one of the most partisan publications in favour of Brexit.
Britain's left-wing tabloid officially declared its view on Wednesday - asking readers to vote Remain. "This paper certainly has its issues with the EU but after the most divisive, vile and political campaign in living memory, we say ... vote remain tomorrow," it said on its front page.
The FT made its view clear back on 15 June. It urged readers to vote remain, and also criticised the referendum campaigns of both sides, claiming: "David Cameron’s referendum gamble has proved to be a futile attempt to heal divisions in the ruling Conservative party. The campaign has split the country. Emotions have trumped facts. Born-again populists rail against the establishment."
Mail on Sunday (print circulation 1.3 million)
Mail on Sunday
In its final edition before the referendum, The Mail On Sunday came out in favour of Remain, warning it is “not the time to risk the peace and prosperity” of the UK. The news surprised many given the largely pro-Brexit coverage from its sister paper the Daily Mail.
The Sunday Times (print circulation 797,000)
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The Sunday Times has come out for Brexit, putting it at odds with its daily counterpart The Times, which has backed Remain.
The Sunday Telegraph (print circulation 370,000)
The Sunday Telegraph came out in favour of Brexit in an editorial on Sunday, joining its sister paper.
The Observer (print circulation 194,000)
The Guardian's sister Sunday paper said voters should not turn their backs on Europe, urging a Remain vote like its sibling. It said: "For an international, liberal and open Britain, we need to be part of the EU".