A Green Beret squad is typically 12 people in a standard Operational Detachment Alpha, or ODA.

Quick Scoop

That 12-person team is the core Green Beret unit and is built to be self- sufficient, with leaders, weapons, engineer, medical, and communications specialists.

Note

Some contexts may refer to smaller split elements taken from that larger 12-person team, but the standard Green Beret operational squad is 12.

TL;DR: 12 people.