How many Espada are there in Bleach, at full strength?

How to get close to this number

Elite groups in serialised action fiction are almost always ten, and knowing that convention answers a whole category of questions. Ten gives a writer enough antagonists for a long arc of individual confrontations, a clean ranking, and a structure the audience can hold in mind. Twelve and nine both appear, but ten dominates.

The numbering detail is the twist worth catching: the ranking starts at zero rather than one, so the strongest member carries the number that looks lowest. Any count based on the highest visible rank will therefore be off by one, which is precisely the kind of trap that makes a fictional-count question worth asking.

The qualifier "at full strength" is doing real work. Membership changes across the arc as members are killed and replaced, so the group is rarely complete at any given moment. Fictional counts are properties of a moment in a story rather than of the story itself, and this question specifies the moment for exactly that reason.