The Guardian is to launch its new, mid-sized format on Monday September 12.
Guardian Newspapers, which has spent £80m on the move including new presses in east London and Manchester, said the new-look Guardian would be the only full-colour national paper in the UK when it hits the newsstands a week on Monday.
The G2 features section is to be relaunched in a smaller, magazine-sized format and the paper is also launching a new daily colour sports section.
The specialist supplements, known as the G3s, will be expanded from tabloid to the new mid-sized format, known in the industry as Berliner, and a new technology section will be introduced on Thursdays to replace the existing Life science supplement.
The Saturday Guardian will launch in the new format on September 17 with nine sections including a new eight-page supplement to be called Family.
Separate Work and Money sections will replace the existing Jobs and Money section, and the Travel and Review sections will change to the Berliner size.
The Observer will switch early next year to the new format, which is used by several mainland European titles including Le Monde but has never before been adopted by a national newspaper in the UK.
The introduction of the new format follows successful relaunches of the Independent and the Times as tabloid-sized newspapers.
Sales of both papers have risen, bucking the general downward trend and hitting sales of the Guardian.
In July sales of the Guardian fell to 358,345, the paper's lowest sale since July 1978. The Times and the Daily Telegraph both registered slight sales rises while the Independent's month-on-month figure fell for the first time in 15 months to 255,603.
"The challenge for us was to remain true to our journalism, now attracting a record worldwide audience online, while at the same time finding a modern print format for a new generation of readers in this country," said Alan Rusbridger, the editor of the Guardian.
"We believe we've found it with the Berliner format, which combines the portability of a tabloid with the sensibility of a broadsheet."
Carolyn McCall, the chief executive of Guardian Newspapers, said: "With this bold move we will have the most modern newspaper in the country alongside the best online newspaper in the world. No other newspaper is so well placed to address the print and internet needs of both readers and advertisers."
The new Guardian design has been created by an in-house team led by the paper's creative editor, Mark Porter, and uses a new typeface, Guardian Egyptian.
Internationally, the Guardian will be printed in the Berliner format in Paris, Frankfurt, Madrid, Marseilles and New York.
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