CIDR and subnet calculator
Enter an IPv4 address with a prefix, such as 10.0.0.0/8, to see its network range, netmask and host count. Everything runs in your browser; nothing you type is sent to our servers.
| Network address | 192.168.1.0 |
|---|---|
| Broadcast address | 192.168.1.255 |
| First usable host | 192.168.1.1 |
| Last usable host | 192.168.1.254 |
| Netmask | 255.255.255.0 |
| Wildcard mask | 0.0.0.255 |
| Prefix length | /24 |
| Total addresses | 256 |
| Usable hosts | 254 |
How to read the results
The network address and broadcast address mark the edges of the subnet. The usable host range is what you can assign to devices. The netmask and wildcard mask are two ways of writing the same boundary.
Frequently asked questions
- What does /24 mean in a CIDR address?
- The number after the slash is the prefix length: how many leading bits identify the network. /24 means the first 24 bits are the network, leaving 8 bits for hosts, which gives 256 addresses and 254 usable hosts.
- Why are the first and last addresses not usable?
- In a normal subnet the first address is the network address and the last is the broadcast address. Neither can be assigned to a device, so they are excluded from the usable host count. Subnets /31 and /32 are the exceptions.
- What is a wildcard mask?
- A wildcard mask is the inverse of the netmask. Firewalls and routers such as Cisco IOS use it in access-list rules, where a 0 bit means the address must match and a 1 bit means it can vary.