According to a leak coming from Nokia’s Beijing factory (its largest factory) the maximum production capacity is 2,000,000 Lumia devices per month; of which only 600K are Lumia 920s.
Nokia’s biggest factory in Beijing can only produce 2 million Windows Phones per month, consisting of 20,000 Nokia Lumia 920’s per day, 25,000 Lumia 820s and 20,000 Lumia 620.
However those numbers really aren’t too bad; assuming that all Lumia 920s produced have been sold (and as far as we’ve seen that looks like the case); and also assuming that no production had started until after the Lumia 920 announcement (Sept. 5th-4 months ago) then accordingly there should have been 2.4 Million Lumia 920s made from the Beijing factory alone.
Besides the Beijing factory Nokia has another 7 global factories, working on the crazy assumption that all these factories can only work at an average of 25% the efficiency of the Beijing factory (which would mean 500K Lumias, 150K of which would be 920s) = 150,000*7= 1,050,000 Lumia 920 devices. Adding up the 2.4 million from the Beijing and the 1.05 from the rest of the world we get 3.45 Million Lumia 920s (and 5.5 Million lumia total-920+820+620); of course that’s all on the bare minimum assumption that production only started after the launch event, and that all the global factories are only working at 25% the efficiency of the Beijing factory. Suddenly that 7 Million number doesn’t sound too far fetched does it?