The magazine will drop down to a bastard-A4 size from its current tabloid shape. The paper's pagination will also increase to compensate for the size drop.
The logo will be slightly reworked and the covers will be glossy on a weekly basis, rather than just on special issues.
NME publisher IPC Media called the reformatting a "marginal resizing". A spokewoman said the new size is not a regular magazine size, but that it has had "1.5 inches chopped off its height so it can fit on the newsstand and that its size is still unique".
The 50th anniversary issue, due out on April 17, will contain a number of special features such as a top 50 list of music icons in the history of the NME and a history of the rise of the paper.
It will contain top music celebrities pictured with their first ever NME covershoot and exclusive photos and interviews including David Bowie, Blur, Oasis, The Prodigy and John Lydon.
The birthday of the title is being commemorated by an exhibition of 50 classic rock photographs chosen from the NME's archive at The Eyestorm Gallery in London on April 17. An auction of the some signed photos willl be held, the proceeds of which will go to the War Child charity.
These pictures will published in a special NME supplement, which goes on sale on April 24. This will be the first of a series of supplements being released throughout the year, including the top 50 NME covers and the 50 greatest albums of all time.
Neil Robinson, NME publishing and online director, said: "The magazine market is as congested and competitive as ever and over the last 10 years the current floor position of NME in newsagents has been marginalised.
"With an improved display position, investment in the editorial product and major awareness of the NME through its 50th-year activity, I feel confident we are set for a very exciting year ahead."
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