Subnet calculator (CIDR)
Enter an address with a prefix — 192.168.1.10/24 or 2001:db8::/48 — and get the whole breakdown at once.
Runs entirely in your browser — nothing you enter is sent to our servers.
- Network
- 192.168.1.0/24
- Netmask
- 255.255.255.0
- Wildcard
- 0.0.0.255
- Broadcast
- 192.168.1.255
- First host
- 192.168.1.1
- Last host
- 192.168.1.254
- Usable hosts
- 254
- Total addresses
- 256
- Scope
- private (RFC 1918)
- Class
- C
- Mask in binary
- 11111111.11111111.11111111.00000000
How it works
For IPv4 you get the network and broadcast addresses, the mask in dotted and binary form, the wildcard (used in ACLs and OSPF) and the usable host range. /31 and /32 are handled the way routers treat them: point-to-point links and single hosts, no network or broadcast to subtract. For IPv6 the calculator shows the full and compressed forms and the first and last address of the prefix. The scope field flags private, CGNAT, link-local and documentation ranges.
FAQ
How many usable hosts are in a /28?
16 addresses, 14 usable: the first is the network address and the last is broadcast. On a routed /28 the provider or your host often keeps one more for the gateway.
What is a wildcard mask?
The inverted netmask: 0.0.0.255 for /24. Cisco ACLs and some firewalls use it instead of a prefix.
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