About
Paste an IPv4 or IPv6 address with CIDR (e.g., 192.168.1.10/24 or 2001:db8::1/64) and get the network address, first/last host, and total addresses instantly.
Useful for firewall allowlists, VPN routing, server ACLs, and quick design checks. IPv4 results include netmask and broadcast; IPv6 shows network range and size.
All calculations run server-side; no files are uploaded. Perfect for quick sanity checks without opening a separate tool.
FAQ
›Which formats are supported?
IPv4 and IPv6 with CIDR, e.g., 10.0.0.5/16 or 2001:db8::/48.
›What about broadcast?
Shown for IPv4. IPv6 has no broadcast; we show first/last addresses instead.
›Can I see usable hosts?
We show first/last and total addresses; subtract network/broadcast as needed for IPv4.
›Is any data stored?
No. The calculation runs per request; nothing is persisted.
›Why CIDR is required?
Prefix length defines the subnet; without it, network boundaries can’t be derived.
Related Tools
- ASN / Prefix Lookup/tools/network/asn
- What Is My IP?/tools/network/my-ip
- DNS Propagation Checker/tools/network/dns-check
- HTTP Headers & Redirects/tools/network/headers
- TLS/SSL Checker/tools/network/tls-check