| Language | Population | Bloc | Family | Cluster | Band | |
|---|---|---|---|---|---|---|
| ● Polish | 40,162,540 | Indo-European | Slavic | West Slavic | Lechitic | |
| ● Czech | 10,149,700 | Indo-European | Slavic | West Slavic | Czech-Slovak | |
| ● Slovak | 5,039,800 | Indo-European | Slavic | West Slavic | Czech-Slovak | |
| ● Kashubian | 99,000 | Indo-European | Slavic | West Slavic | Lechitic | |
| ● Sorbian, Upper | 18,000 | Indo-European | Slavic | West Slavic | Sorbian | |
| ● Sorbian, Lower | 4,360 | Indo-European | Slavic | West Slavic | Sorbian |