Facebook does not provide a way to sort all Facebook groups by size. However, below is a list of the 20 largest Facebook groups in 2021.
List of 20 of the biggest Facebook groups:
| Facebook Group | Members | Public or Private |
| Evergreen Bangladesh | 11,545,851 | Public |
| HAIRSTYLES | 6,884,957 | Public |
| Our Evergreen Bangladesh | 6,324,077 | Public |
| PRAY UNTIL SOMETHING HAPPENS! [PUSH]! | 4,065,323 | Public |
| Kersh Keepers Official Group | 3,846,287 | Private |
| Be Like Bro | 3,333,869 | Private |
| WWE MONDAY NIGHT RAW | 3,192,986 | Private |
| Pantsuit Nation x Supermajority | 3,093,872 | Private |
| Maths Formulas | 2,947,217 | Public |
| Instant Pot Community | 2,734,067 | Public |
| PRAY UNTIL SOMETHING HAPPENS! [PUSH]! | 2,589,575 | Public |
| OFFICIALLY FAME 🐰 | 2,407,435 | Private |
| View from my window | 2,343,188 | Public |
| Motivational Quotes | 2,343,117 | Public |