The number of cardinals participating in a papal conclave consists of those under the age of 80 at the time the papacy becomes vacant. In the most recent 2025 conclave, there were 252 cardinals in total worldwide, but only 135 were eligible to vote because they were under 80 years old. Of these 135 eligible cardinal electors, 133 actually participated in the conclave, as two were unable to attend due to health reasons
. To summarize:
- Total cardinals worldwide: 252
- Eligible cardinal electors (under 80): 135
- Cardinal electors participating in the 2025 conclave: 133
The conclave requires a two-thirds majority of these electors to elect a new pope, which in 2025 meant at least 89 votes were needed
