useforfreeWhat this does
This subnet calculator works out everything about an IP network from an address and its prefix (like /24) or mask (like 255.255.255.0): the network and broadcast addresses, the range of usable hosts, how many devices fit, the subnet and wildcard masks, and whether the address is private or public. It also shows the bits in binary and can split a network into smaller subnets. IPv6 works too.
How to use it
- Type an address such as 192.168.1.10/24, 10.0.0.5 255.0.0.0 or 2001:db8::/48.
- Change the prefix from the list to see how the network grows or shrinks.
- Pick a size under Split into to list the smaller subnets.
FAQ
What does /24 mean?
It is CIDR notation: the first 24 bits of the address are the network and the rest identify devices. A /24 equals the mask 255.255.255.0 and holds 256 addresses, 254 of them usable.
Why are two addresses not usable?
In IPv4 the first address names the network itself and the last is the broadcast address. Point-to-point links (/31) and single hosts (/32) are the exceptions. IPv6 has no broadcast address.
Which addresses are private?
For IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. For IPv6, unique local addresses start with fc00::/7. The calculator shows the type of every address you enter.