Work out a subnet from CIDR
Planning or troubleshooting a network means knowing a subnet's boundaries: the network address, the broadcast address, the usable host range, and how many hosts it holds. Doing that in binary by hand is slow. This calculator takes an address and CIDR prefix and returns all of it at once.
How to use it
- Enter an IP address and the CIDR prefix (such as /24).
- Read the network and broadcast addresses, host range, and count.
- Use it to plan addressing or check a device's subnet.
Where it helps
- Designing address ranges for a network.
- Checking whether two addresses share a subnet.
- Sizing a subnet to the number of hosts you need.
Questions people ask
Why are usable hosts two fewer than the total? The first address is the network itself and the last is the broadcast address, so neither is assigned to a host.
Is my input stored? No — the calculation runs in your browser.