Subnet calculator
Enter an address with a prefix, such as 192.168.1.10/24, to see the network it belongs to and everything that can be worked out about it.
For example 10.0.0.1/8, 192.168.1.10 255.255.255.0 or 2001:db8::1/48.
Network
192.168.1.0/24
Private address (RFC 1918)
- Network address
- 192.168.1.0
- Broadcast address
- 192.168.1.255
- Usable addresses
- 192.168.1.1 – 192.168.1.254
- Usable hosts
- 254
- Total addresses
- 256
- Subnet mask
- 255.255.255.0
- Wildcard mask
- 0.0.0.255
- Prefix
- /24
- Class (historical)
- C
- Reverse DNS
- 10.1.168.192.in-addr.arpa
In binary
- Address
- 11000000.10101000.00000001.00001010
- Subnet mask
- 11111111.11111111.11111111.00000000
Split into smaller subnets
4 subnets with 62 usable hosts each.
| Subnet | Usable addresses | Broadcast address |
|---|---|---|
| 192.168.1.0/26 | 192.168.1.1 – 192.168.1.62 | 192.168.1.63 |
| 192.168.1.64/26 | 192.168.1.65 – 192.168.1.126 | 192.168.1.127 |
| 192.168.1.128/26 | 192.168.1.129 – 192.168.1.190 | 192.168.1.191 |
| 192.168.1.192/26 | 192.168.1.193 – 192.168.1.254 | 192.168.1.255 |
How big a network do you need?
Smallest IPv4 network: /26 (255.255.255.192) with 62 usable hosts.
How it works
An IP address has a network part and a host part. The prefix after the slash says how many bits from the left belong to the network: in 192.168.1.10/24 the first 24 bits, 192.168.1, are the network and the last 8 bits the host. This notation is called CIDR and replaced the old network classes A, B and C in 1993.
The subnet mask says the same as the prefix but is written as an address: /24 is 255.255.255.0. The wildcard mask is the mask with its bits inverted, 0.0.0.255, and is used for example in router access lists.
In IPv4 the first address of a network identifies the network itself and the last is for broadcasting to all hosts, so a /24 with 256 addresses has 254 usable hosts. The exceptions are /31, used for links between two routers where both addresses are used under RFC 3021, and /32, which is a single address.
Ranges such as 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 are private and used in local networks. 100.64.0.0/10 is used by providers that share public addresses between customers, and a computer that cannot find a DHCP server gives itself an address in 169.254.0.0/16.
IPv6 addresses have 128 bits and are written in hexadecimal groups, with a run of zeros shortened to ::. A typical local network is a /64, and organisations are often given a /48, which holds 65,536 such networks. IPv6 has no broadcast address, so every address in the block counts.
The split shows how the network can be divided into equal smaller subnets. Each step in the prefix halves the size and doubles the number.