Edge-joined unit squares of the square lattice — the classic polyform family, home of the twelve pentominoes.
The 12 free pentominoes.
| Figure | Order | Free | One-sided | Fixed | Verified |
|---|---|---|---|---|---|
| monomino | 1 | 1 | 1 | 1 | ✓ 15/15 |
| domino | 2 | 1 | 1 | 2 | ✓ 15/15 |
| tromino | 3 | 2 | 2 | 6 | ✓ 15/15 |
| tetromino | 4 | 5 | 7 | 19 | ✓ 15/15 |
| pentomino | 5 | 12 | 18 | 63 | ✓ 15/15 |
| hexomino | 6 | 35 | 60 | 216 | ✓ 15/15 |
| heptomino | 7 | 108 | 196 | 760 | ✓ 15/15 |
| octomino | 8 | 369 | 704 | 2,725 | ✓ 15/15 |
| nonomino | 9 | 1,285 | 2,500 | 9,910 | ✓ 15/15 |
Reference sequences: Free A000105, One-Sided A000988, Fixed A001168.