IPv4 CIDR calculator
Split an IPv4 CIDR into network, broadcast, mask, wildcard, and usable hosts in your browser. Nothing is uploaded.
IPv4 only. Calculate in this tab.
How to use the IPv4 CIDR calculator
- Paste an address with a prefix, such as 192.168.10.45/24, or a dotted mask.
- Click Calculate.
- Copy the network, broadcast, and wildcard for ACLs or routing labs.
What you get
Prefix, dotted mask, Cisco-style wildcard, network, broadcast, first and last host, and a usable-host count. /31 follows RFC 3021 (two addresses). /32 is a single host. IPv4 only — no IPv6 in this pass. Pair it with the CCNA subnetting notes at /what-is-subnetting/.
Nothing is uploaded
Math stays in the tab.
IPv4 CIDR calculator FAQ
Classful addressing?
The class row is historical (A–E). Routing today is CIDR.
Private ranges?
10/8, 172.16/12, and 192.168/16 are flagged as RFC 1918.