Subnet calculator
Calculate network address, broadcast, and host range from CIDR.
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Tool guide
Subnet calculator: how it works
Practical information to understand the result and use this tool correctly.
About Subnet calculator
CIDR notation combines an IPv4 address with a prefix length (e.g. 192.168.1.10/24) to describe a subnet.
This calculator derives network and broadcast addresses, usable host counts, and the dotted mask.
It does not design hierarchical addressing plans—use it to check a single prefix quickly.
How to use it
- 1Enter an IPv4 address and prefix length (0–32).
- 2Read network, broadcast, and host range.
- 3Confirm the result matches your routing design.
Frequently asked questions
- What about /31 and /32?
- Point-to-point and host routes use special host counts; the tool reports 0 usable hosts if the prefix is ≥ 31.
- Private ranges?
- 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 are private. The calculator does not restrict them.