Subnet calculator
Network, broadcast, mask and host range for any IPv4 or IPv6 prefix, worked out on your device.
Runs entirely in your browser — nothing is sent to us.
Write it as CIDR (192.168.10.0/26), as an address and a mask (192.168.10.0 255.255.255.192), or as a single address.
Try
Enter an address and a prefix to see the block it belongs to.
What it calculates#
- The network address and, for IPv4, the broadcast address of the block your input belongs to.
- The subnet mask and wildcard mask in dotted decimal, for IPv4.
- The first and last usable host, and the total and usable address counts.
- Whether the address is public, private, shared (CGNAT), loopback, link-local or reserved.
- The binary form of an IPv4 address with the network and host bits marked.
- Whether another address is inside the block.
- A split of the block into equal smaller subnets, with the ranges listed.
What you can type#
| Form | Example |
|---|---|
| CIDR notation | 192.168.10.0/26 |
| Address and subnet mask | 192.168.10.0 255.255.255.192 |
| IPv6 with a prefix | 2001:db8::/32 |
| A single address | 198.51.100.7 (read as a /32, or /128 for IPv6) |
An address with host bits set, such as 192.168.10.77/26, is fine: the calculator finds the block it belongs to.
A worked example#
| Result | Value |
|---|---|
| Network address | 192.168.10.64 |
| Broadcast address | 192.168.10.127 |
| Subnet mask | 255.255.255.192 |
| Wildcard mask | 0.0.0.63 |
| Usable hosts | 62, from 192.168.10.65 to 192.168.10.126 |
The CIDR and subnetting guide works this one out by hand, so you can check the method as well as the answer.
Details worth knowing#
- A `/31` has two usable addresses, not zero, because point-to-point links use both ends (RFC 3021). A
/32is one host. - IPv6 has no broadcast address. Every address in a block can be assigned, and a
/64is the normal size of a subnet. - The legacy class shown for IPv4 is historical. Nothing routes by class today: see IPv4 address classes.
The calculation runs entirely in your browser, so addresses you type, including private ones from your own network, are never sent anywhere.
Related guides
- CIDR notation and subnetting explainedCIDR notation like 192.168.10.0/26 says how many bits name the network. How to read it, calculate a subnet by hand, and split a network into smaller ones.
- IPv4 address classes explainedClassful addressing split IPv4 into classes A to E by the first bits. The ranges, default masks and host counts, and why CIDR replaced the system in 1993.
- Public vs private IP addressesYour devices have a private address from your router and share one public address with the internet. The ranges, how NAT links them, and how to tell which is which.
- IPv4 vs IPv6: what changedIPv4 has 4.3 billion addresses and IPv6 has 340 undecillion. How the two differ, how to read IPv6 notation, why both are in use, and what it means for your privacy.