Subnet Calculator
Network and broadcast addresses, host range and host count for an IPv4 address with a prefix or subnet mask.
Your network
Filled in with example values. Replace them with your own.
Results update as you type.
Result
Network: 192.168.1.0/24
Network
192.168.1.0/24
- Subnet mask
- 255.255.255.0
- Wildcard mask
- 0.0.0.255
- Network address
- 192.168.1.0
- Broadcast address
- 192.168.1.255
- Host range
- 192.168.1.1 – 192.168.1.254
- Usable hosts
- 254
- Total addresses
- 256
In binary
- Address
- 11000000.10101000.00000001.00001010
- Mask
- 11111111.11111111.11111111.00000000
- Network
- 11000000.10101000.00000001.00000000
The first 24 bits are the network; the rest identify hosts.
How it’s calculated
Network
192.168.1.10 AND 255.255.255.0 = 192.168.1.0
Broadcast
192.168.1.0 OR 0.0.0.255 = 192.168.1.255
Usable hosts
2^(32 − 24) − 2 = 254
How the subnet calculator works
Enter an IPv4 address and either a prefix length (such as 24) or a subnet mask (such as 255.255.255.0). The calculator combines them bit by bit to find the network the address belongs to, its broadcast address, the range of host addresses and how many there are.
The formula
Network = Address AND Mask
Broadcast = Network OR Wildcard
Usable hosts = 2^(32 − Prefix) − 2
Worked examples
- 192.168.1.10/24: network 192.168.1.0, broadcast 192.168.1.255, hosts 192.168.1.1 to 192.168.1.254, 254 usable. It is a private address (RFC 1918).
- 10.20.30.40/20 (mask 255.255.240.0): each /20 spans 16 values of the third number, so the network is 10.20.16.0 and the broadcast 10.20.31.255, with 4,094 usable hosts.
Frequently asked questions
What does /24 mean?
It is CIDR notation: the first 24 of the 32 bits of the address identify the network, and the remaining 8 identify hosts. A /24 is the same as the mask 255.255.255.0 and contains 256 addresses.
Why are there 2 fewer usable hosts than addresses?
In a normal subnet the first address identifies the network itself and the last is the broadcast address, so neither is given to a device. The exceptions are /31 (two usable addresses on a point-to-point link, RFC 3021) and /32 (a single address).
What is a wildcard mask?
The subnet mask with every bit flipped: 255.255.255.0 becomes 0.0.0.255. Some router and firewall configurations use it instead of the subnet mask.
What are private addresses?
The ranges 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 are set aside by RFC 1918 for private networks and are not routed on the public internet. The calculator also recognises loopback, link-local, shared (carrier-grade NAT) and multicast addresses.
Does it work for IPv6?
Not yet. This calculator is for IPv4 addresses only.