The /32 subnet
A /32 subnet uses the mask 255.255.255.255 and holds 1 addresses, 1 of them usable.
A /32 is a single IPv4 address. Its mask is 255.255.255.255 and it describes exactly one host, which is why you see /32 on host routes, loopback entries, and firewall rules that match one machine.
Because a /32 has no room for a network or broadcast address, tools count it as one usable address rather than subtracting the usual two. Access lists and routing tables use /32 to pin traffic to a single endpoint.
Below you can see the exact network, broadcast, and host range for any /32 you enter, calculated instantly in your browser.
Calculate a /32 network
Accepts CIDR (192.0.2.0/24), IP + mask (192.0.2.0 255.255.255.0), or a bare IP (defaults to /24).
11000000.00000000.00000010.0000000011111111.11111111.11111111.11111111Example: 192.0.2.0/32
Taking 192.0.2.0/32 as a worked example, the block breaks down like this:
| Network address | 192.0.2.0 |
|---|---|
| Usable range | 192.0.2.0 - 192.0.2.0 |
| Broadcast address | 192.0.2.0 |
| Total addresses | 1 |
| Usable hosts | 1 |
| Size | 1/256 of a class C block |
Frequently asked questions
What is the subnet mask for a /32?
A /32 uses the subnet mask 255.255.255.255. Its wildcard mask, used in access lists, is 0.0.0.0.
How many hosts are in a /32 subnet?
A /32 has 1 total addresses and 1 usable hosts (the total minus the network and broadcast addresses, except for /31 and /32).
What is a /32 used for?
Single host route. It is equivalent to 1/256 of a class C block.
How do I calculate a /32 network?
Set the host bits to zero for the network address and to one for the broadcast address. The calculator on this page does it for any /32 block you enter.