Subnet calculator: IPv4 and IPv6, instantly
How does this check work, and what does the result tell you?
Enter a CIDR or an address and mask and AdminKit returns the network address, broadcast address, usable host range and host count, for IPv4 and IPv6, calculated entirely in your browser as you type with nothing sent to a server at any point.
Part of the IP & network cluster — more tools, guides and terms on ip & network.
- Network address
- 192.168.1.0
- Broadcast address
- 192.168.1.255
- Subnet mask
- 255.255.255.0 (/24)
- Wildcard mask
- 0.0.0.255
- Usable host range
- 192.168.1.1 – 192.168.1.254
- Usable hosts
- 254 (of 256 total addresses)
What the result means
The usable host range excludes the network and broadcast addresses for ordinary IPv4 subnets; /31 and /32 are exceptions with their own usable ranges, as shown above.
Next step
Check your own public IP, or look up DNS records for a domain in this range.
Keep this result
Copy a link to this check so you can share it or run it again later. Want a heads-up when this result changes? Talk to our team and we'll set it up for you.
How it works and limits
Enter an address with a prefix (192.168.1.0/24) or a dotted mask (10.0.0.0/255.255.0.0) for IPv4, or an address
with a prefix for IPv6 (2001:db8::/64). The result updates as you type — every calculation happens with plain
arithmetic in your browser’s JavaScript engine, nothing is sent to a server.
Reading the result
For IPv4: the network and broadcast addresses bound the subnet, the usable host range excludes both (except for /31 point-to-point links, RFC 3021, where both addresses are usable, and /32, a single host). For IPv6: there is no broadcast address — every subnet is normally sized at /64 for address autoconfiguration (SLAAC), so a /64 has 264 addresses regardless of how many devices actually use it. Every device on that /64 still needs its own firewall rules once it has a globally routable address — see IPv6 and home devices: why no NAT means a firewall.
Limits
- This is address-plan arithmetic, not a live reachability check — it does not tell you whether any address in the range is actually in use.
- IPv6 addresses are shown in their RFC 5952 canonical compressed form.
- For a single IPv6 address’s prefix/interface-id split, category, and any MAC address embedded in a modified EUI-64 interface id, see the IPv6 info tool instead.
- This calculator sizes one block at a time; to collapse a whole list of addresses and CIDR blocks into the fewest prefixes that exactly cover them, use the CIDR aggregator instead.
See subnet and CIDR basics: reading a subnet calculator result for a worked walkthrough of the output fields, and best free subnet calculators, compared for how this client-side, nothing-sent-to-a-server tool stacks up against other free options. Reference: subnet.
Frequently asked questions
Does this tool send my input anywhere?
No — the math runs entirely in your browser.
Why is the IPv6 host count so large?
A typical IPv6 /64 allocation has 2^64 addresses — far more than any subnet needs; it is sized for address autoconfiguration, not scarcity.
What is a /31 subnet for, if it has no usable host range in the normal sense?
RFC 3021 defines /31 specifically for point-to-point links (e.g. between two routers), where both addresses in the pair are usable and no network/broadcast address is needed, since there is no broadcast domain with only two hosts.
Can I use any address inside an IPv4 subnet, or are some reserved?
The network address (all host bits zero) and the broadcast address (all host bits one) are reserved and not assignable to a device, except in a /31 or /32 as noted above. Every other address in the range is usable.