IPv4 Subnet Calculator
Enter an IP address and CIDR prefix to get the network address, broadcast address, subnet mask, host range and host count.
How it works
- 1
Enter an IPv4 address
Like 192.168.1.100.
- 2
Set the CIDR prefix
From 0 to 32, like 24.
- 3
Read the results
Network, broadcast, mask, usable range and host counts.
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Frequently asked questions
The first is the network address and the last is the broadcast address (except for /31 and /32).
How subnetting works
A CIDR prefix such as /24 says how many leading bits of the address identify the network. The remaining bits identify hosts. A /24 leaves 8 host bits, so 256 addresses, of which 254 are usable because the first is the network address and the last is the broadcast address.
Subnet planning is a core network-admin task: splitting an office network, allocating cloud VPC ranges, or checking whether two addresses are in the same subnet. Calculations run in your browser and nothing is sent anywhere.