IP Subnet Calculator
Compute network, broadcast, mask and host range from a CIDR.
Enter an IPv4 CIDR (e.g. 192.168.1.0/24) and get the network address, broadcast address, subnet mask, wildcard mask, first and last usable hosts, total addresses, usable host count, and binary representations.
Common use cases
- Plan an IP allocation for a new VLAN or VPC subnet
- Verify that two CIDRs don't overlap before configuring a VPN
- Convert between dotted-quad masks and prefix lengths
- Teach networking fundamentals with a worked CIDR example
Frequently asked questions
Is IPv6 supported?▾
Not yet — this calculator is IPv4 only. For IPv6 prefix math, use a dedicated tool like ipv6-calculator.
What does 'usable hosts' mean?▾
Total addresses in the subnet minus the network and broadcast addresses. /31 and /32 prefixes are special cases where all addresses are usable (point-to-point links / single hosts).
Why does my /30 only have 2 usable hosts?▾
A /30 has 4 addresses total: network, two hosts and broadcast. So only 2 are assignable to devices.
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