Match a prefix to a dotted-decimal mask
An IPv4 mask has p leading one bits followed by 32 − p zero bits. For /26, the final octet is 11000000 in binary, so the mask is 255.255.255.192. Each /26 spans 64 addresses and normally offers 62 host addresses.
Splitting 192.0.2.0/24 into /26 networks gives 192.0.2.0/26, 192.0.2.64/26, 192.0.2.128/26 and 192.0.2.192/26. A host address entered with a prefix is normalized to its containing network before splitting.
Build a hierarchy for unequal allocations
For variable-length subnet masking, first generate the larger blocks, then split only the leaves that need smaller allocations. For instance, keep a /26 for one segment and split another /26 into two /27s. Each child stays inside its parent and equal-sized siblings do not overlap.
Bulk split subdivides every eligible leaf, preserving smaller blocks that already have an equal or longer prefix. Collapse controls simplify the view. CSV and copy reflect the expanded/collapsed hierarchy across every result page; expand all levels before exporting individual leaf allocations.
Check the /31 and /32 exceptions
The usual 2^(32 − p) − 2 usable-host formula applies through /30. A /31 point-to-point link has two usable endpoints, while a /32 names one address. The host counts shown here follow those rules; the appropriate prefix still depends on your link type and routing design.