Enter an IP address
Type any IPv4 address, such as one from a router config or a server's private network.
IP Subnet Calculator
Enter an IPv4 address and CIDR prefix or subnet mask to instantly see the network address, broadcast address, usable host range and more.
How it works
Add a CIDR prefix or mask
Switch between /24-style CIDR notation and a dotted mask like 255.255.255.0 — either works.
Read the full breakdown
Network address, broadcast address, usable host range and total addresses are all computed instantly.
FAQ
What does the /24 in a CIDR mean?
The number after the slash is the prefix length — how many leading bits of the 32-bit address identify the network. A /24 means the first 24 bits are the network, leaving 8 bits (256 addresses) for hosts.
Why is the usable host count two less than the total?
The first address in a subnet is reserved as the network address and the last is reserved as the broadcast address, so neither can be assigned to a host (except in /31 and /32 special cases).
Can I enter a subnet mask instead of a CIDR prefix?
Yes. Switch to dotted-mask mode and enter something like 255.255.255.0 — it's automatically converted to the equivalent CIDR prefix.