With the additional draw of Pamela Anderson on the cover for the first time since March 1996, the publisher hopes to sell around 120,000 of each one-off size in addition to its normal print run of around 600,000 regular-size copies.
Andrew Morley, FHM UK's commercial director, said the move was about offering readers new reasons to come to the magazine and providing advertisers with more copy sales, rather than bespoke ads. The issue, out today, was kept a secret to avoid spoilers from rival publishers.
"The monthly market has become pretty tough and mercenary with our rivals offering DVDs as gifts. It's really important that we exhibit market-leading behaviour," he said.
The content will be the same across the three sizes of the magazine, but the small and the large versions will include special 16-page supplements celebrating their size.
The 230x170mm Glamour-sized small supplement features the shortest basketball player in the US NBA league and the world's shortest island airstrip in Hawaii. In its 350x257mm counterpart, readers get close up with the world's largest cockroach and biggest battleship. The regular format measures 300x220mm.
FHM developed the concept following sales spikes for FHM Russia and FHM Spain when they produced special large issues, and has claimed it as a global publishing first.
David Pullan, managing director of FHM Worldwide, said: "This latest magazine innovation builds on FHM's reputation for challenging and reinvigorating the men's market, offering interest and value to readers and advertisers alike."
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