IPv4 subnet calculator
Find the network, broadcast, host range, mask and address type from a CIDR block.
A clear answer. Here’s how.
Applies the prefix as a 32-bit mask: network = address AND mask, broadcast = network OR wildcard, and usable hosts = 2^(32−prefix) − 2. A /31 has two usable addresses and no broadcast (RFC 3021), and a /32 is a single host. Dotted masks must be contiguous ones then zeros. Address types follow the IANA special-purpose registry ranges listed in the RFCs below. This is IPv4 arithmetic only; it does not discover real networks.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- IPv4 address with prefix or mask
- 192.168.1.130/26
Example result
- CIDR notation
- 192.168.1.128/26
- Network address
- 192.168.1.128
- Broadcast address
- 192.168.1.191
- First usable address
- 192.168.1.129
- Last usable address
- 192.168.1.190
- Usable hosts
- 62
- Total addresses
- 64
- Subnet mask
- 255.255.255.192
- Wildcard mask
- 0.0.0.63
- Mask in binary
- 11111111.11111111.11111111.11000000
- Address entered
- 192.168.1.130 (class C)
- Address type
- Private (RFC 1918)
Usable hosts exclude the network and broadcast addresses, except /31 (two usable addresses, RFC 3021) and /32 (one host route). Classes are historical; modern routing uses CIDR prefixes (RFC 4632).