To calculate a subnet, enter an IP address and CIDR prefix such as 192.168.1.0/24 into the Subnet Calculator. It returns the network address, broadcast address, subnet mask and usable host range.
How to use the Subnet Calculator (CIDR)
- Enter the IP address.
- Enter the CIDR prefix length.
- Read the network, broadcast, mask and host range.
- Plan your addressing.
Worked example
192.168.1.0/24 has the mask 255.255.255.0, network 192.168.1.0, broadcast 192.168.1.255 and 254 usable hosts from .1 to .254.
Tips and common mistakes
- Usable hosts are 2 to the power of the host bits, minus 2.
- A larger prefix number means a smaller network.
- Keep room for growth when planning subnets.
Frequently asked questions
What is CIDR?
A notation like /24 that says how many bits are the network part of the address.
Why subtract 2 hosts?
One address is the network and one is the broadcast.
Is it private?
Yes.