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Subnet Calculator
IPv4 · runs in your browser, nothing is sent anywhere
192.168.1.10 · 192.168.1.10/24 · 10.0.0.1 255.255.255.0
| Network | — |
|---|---|
| Usable range | — |
| Broadcast | — |
| Subnet mask | — |
| Wildcard | — |
| Usable hosts | — |
| Scope | — |
Network bits / host bits
—
How the arithmetic works
The prefix says how many bits belong to the network. AND the address with the mask and the host bits fall away, leaving the network address. OR it with the inverted mask and every host bit turns on, giving the broadcast. Everything between those two is addressable.
Two cases trip up calculators, including some commercial ones:
- /31 has no broadcast address. RFC 3021 makes both addresses usable on a point-to-point link, so the answer is two hosts, not zero. A tool that blindly computes 2n − 2 gets this wrong.
- /32 is a single host. No network address, no broadcast, one usable address — which is why you see it on loopbacks and host routes.
More tools are coming. VLSM planning, a wildcard-mask helper for ACLs, and a cable-standard reference are on the list. If there is one you keep reaching for, say so in the forum.