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IP/24SubnetLens

See your subnet.

Enter an IP address and CIDR prefix to instantly visualise the network, usable range, broadcast address and address count. Drag the prefix and watch the block split. Calculated entirely in your browser.

Try
192.168.1.0/24
Entered192.168.1.42
254usable addresses
First usable
192.168.1.1
Last usable
192.168.1.254
Subnet 192 dot 168 dot 1 dot 0 slash 24. 256 total addresses, 254 usable host addresses. First usable 192 dot 168 dot 1 dot 1, last usable 192 dot 168 dot 1 dot 254. Broadcast 192 dot 168 dot 1 dot 255. The entered address 192 dot 168 dot 1 dot 42 sits at offset 42 inside the block.
Usable hosts256 total
254
Common
Usable hosts
254
256 total
Bits
24 network/8 host

One field

Type 192.168.1.42/24, a space instead of the slash, or a dotted mask like 255.255.255.0. IPv4 and IPv6 are detected for you — there is nothing to switch.

One idea

The block above is the address space. Drag the prefix one bit longer and it splits in half in front of you; the half holding your address stays lit. That is all a CIDR prefix has ever meant.

Nothing leaves

No account, no database, no lookup service. The maths runs in this tab, so the addresses you type are never sent anywhere — including to us.