CIDR and subnet calculator
Write firewall allowlists and probe IP ranges without off-by-one mistakes.
| Network | 10.42.8.0/22 |
|---|---|
| Netmask | 255.255.252.0 |
| Wildcard mask | 0.0.3.255 |
| Broadcast | 10.42.11.255 |
| First host | 10.42.8.1 |
| Last host | 10.42.11.254 |
| Addresses | 1,024 |
| Usable hosts | 1,022 |
/31 networks follow RFC 3021 (two usable addresses). IPv6 has no broadcast address.
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Start monitoringHow it measures
- Bitwise arithmetic over the parsed address; /31 follows RFC 3021 with two usable hosts.
- IPv6 counts above 10^15 are shown as powers of two.
Limits
- No reserved-range classification; use the reverse DNS tool's policy or IANA tables for that.