This makes good points but I believe that it is the wrong answer. Yes, there is no central membership roster. But a competent domestic intelligence organization like the FBI should have an idea how many violent activists there are, how many non-violent activists. They might get it wrong in any one case, but on average the numbers should hold. I don't know if they publish those numbers, but you see intelligence officials talking about right-wing vs. left-wing threats, lone wolves, etc. They must have more than their gut feeling for that.

@Megapteranovaeangliae, the question was if there are numbers. I think there are approximate numbers and I consider it likely that they are public, in some report or public hearing transcrips. That would make the last paragraph of the answer wrong.

@o.m. but that would not make all the antifa "members". There are some BLM people who may be violent activist, and there are some antifa that may be violent activist. But that is a personal definition, not a "membership". Some of those also may be homosexual, and some of those may prefer mayo to ketchup. Maybe the FBI has this info, but it kind of distracts from the main point of this answer: its a political ideology, not a group with members. Maybe the FBI also has a list of possible-violent dog lovers, that does not make them an organization though.

In short: its wrong to see it as "antifas that are violent" (implies membership of antifa) and its more like "antifas, and violents activist" (members of 2 sets of groups).

@o.m. How do you determine whether someone is a member? As I see it, if you oppose fascism, enough to protest it at least once in any way whatsoever, you are anti-fa.

@user253751 if you oppose fascism, you are antifascist but you are not automatically part of anti-fa. Same as you're not part of Anonymous just because you hack something or make information public. You also need to claim the title/association. Obviously that is also a problem because people get lumped in together under an umbrella term as soon as there is news coverage and political leveraging going on. Btw. that also means a lower threshold for an estimation could be sold anti-fa badges^^

@HAEM walks like a duck...

@user253751, the authorities will have some idea how many drug addicts there are in an area, or how many illegal immigrants, or how many tax dodgers. Those numbers are not exact, but they are the basis of policy decisions. I expect the same for groups which the authorities lump under militant antifa.

You really don't need to self-identify as part of a movement to be part of a movement. A rose by any other name and all that.

Antifa in Europe definitely has members. Very loosely organized comprised by mostly anarchists. Also to some degree what could be characterized as leaders.

Since there is no central leadership, "membership" is sort of self-identified. An agency like the FBI could categorize someone as a member if they see that the person claims to be a member (either directly by saying so), or by participation in their activities with other self-identified members (going to a protest or meeting, helping to organize such meetings or protests).

I know precisely no one who self-identifies as a "member" of Antifa, because such a "membership" would not have any consequences other than make the person claiming to be a member sound uninformed and potentially unreliable -- you don't want people who are in it for the satisfaction of being part of something bigger, for the adventure, or for making a name for themselves. The movement is very explicit about not making antifascism part of your identity any more than cleaning your house is: it's a necessity, not something to be celebrated.

@SimonRichter antifa groups in my region have anti-fa badges there is very much a loose membership feeling they have and portray. Same with anonymous, you can support their goals but you're only really part of it when you make a video speaking in their name, otherwise you're just a supporter (or send a message etc pp). Perhaps the self-portrayal is different in the US but still if it is about more than being anti fascist and you attribute any more behaviour and convictions then it is a specific subgoup and just attributing someone wildly into it is very arbitrary.

@o.m. - No, its the right answer. All "antifa" really means is "anti-fascist". One could make an argument that most of the USA is anti-fascist. The term is mostly used by those who consider themselves opponents. The question is akin to asking how many White Supremacists there are in the USA.

@T.E.D. It is an organization in the sense that people claim association while participating in activities related to common goals. It may not have a central leader... but for all other intents and purposes, it's an organization that claims to be against fascism, while it actively perpetrates fascism against all those who don't agree with it's loose viewpoints. - "Don't agree? We'll beat you in the streets until you see things our way..."

@T.E.D. I think you have little evidence to prove that either way. People claiming they're against fascism or racism while they flip over cars and loot stores is as close as we'll get to active involvement... and that's close enough for me.

@SimonRichter that might well be the ideal, but again, same with anonymous, the goal there is also that it could be anyone, but only the ones who actually do something and claim the anonymous tag are part of anonymous. Same for anti-fa. You can say all "antifascist people" but "anti-fa" is a clear association tag that has more than just being a good person that considers fascism bad. But alas, this is not a discussion forum and we're getting off-topic with this I guess, so I'm out of this.

@CrackpotCrocodile True, I didn't have to be that charitable, but I've found that a little charity is no bad thing.

@CrackpotCrocodile Then fix your writing. It's beyond deliberate at this point. You DID stoop to that level. You're already there.