CIDR Calculator
Calculate IP ranges, subnet masks, and broadcast addresses from CIDR notation.
——————————————Enter a larger target prefix to generate child networks.
| Subnet | Network | Broadcast | Usable hosts |
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Frequently Asked Questions
Does this CIDR calculator support IPv6 ranges?
No. Its parser only accepts IPv4 CIDR input in dotted-quad form like 192.168.1.0/24, and all of the subnet math is 32-bit IPv4 math.
How does it handle /31 and /32 networks?
The tool has explicit special cases for them. A /31 is shown with 2 usable hosts, and a /32 is shown with 1 usable host instead of subtracting the usual network and broadcast addresses.
Can it split a network into smaller subnets?
Yes. Enter a larger target prefix in “Split into prefix,” and it will generate child subnets plus their broadcast addresses and usable host counts. It only renders the first N results, and that display is capped at 128 rows.
Why is the first usable address sometimes the same as the network address?
That happens on /31 and /32 because the calculator intentionally treats those as special cases. For wider networks it uses network+1 and broadcast-1, but not for those two prefixes.
Does it tell me whether a block is private or public?
Yes. It classifies the network as Private RFC1918, Loopback, Link-local, Multicast, Reserved, or Public, and it also shows the old IP class based on the first octet.