Some smart ponies in the community has done a small census to calculate the size of the brony fandom.
Check it out below!
Recently, someone did a survey on the internet asking random people to rate their level of identification with the "Brony" label. Even though they only had about 1000 answers, after doing some statistical calculations, they could conclude this:
Thus, we can state with a 95% confidence that between 4.0% and 6.8% of the internet-using US population strongly identify as bronies, or approximately 7 to 12.4 million people.Source
And if you take into account that this is just the US, bronies are most likely well into the 8-digit range worldwide. That is, if the survey statistics can stand up to scrutiny. I'd like to see more of these so we are able to average the percentages.
Anyway, that's a lot of bronies!
SEMPER FILLY!