🌐 Subnet Calculator
Subnetting splits an IP network into the network portion and the host portion using a bitmask. Give this calculator any IPv4 address with a CIDR prefix (like /24) and it derives the network address, broadcast address, subnet mask and the full usable host range.
Remember the rule behind the numbers: the all-zeros host address is the network itself and the all-ones address is the broadcast — neither is assignable to a device.
How to use this calculator
Enter an IPv4 address and pick a CIDR prefix, and the calculator returns the network address, subnet mask, broadcast address, usable host count and the full usable IP range.
- Type the IP address into the IP address field, for example 192.168.1.0.
- Choose the CIDR prefix from the dropdown, for example /24.
- Check the hero line for the network address with its prefix.
- Read the subnet mask, broadcast address, usable host count and usable range from the rows below.
Frequently asked questions
What does the Subnet Calculator compute?
It takes an IP address and a CIDR prefix and derives the network address, the subnet mask in dotted form, the broadcast address, the number of usable host addresses, and the first-to-last usable IP range.
What does CIDR notation like /24 actually mean?
The number after the slash counts how many of the 32 address bits belong to the network portion. A /24 mask, written 255.255.255.0, leaves 8 host bits, which is why such a network holds 254 usable devices.
Can you give a worked example?
Enter IP address 192.168.1.0 with CIDR prefix /24. The network address is 192.168.1.0/24, the mask is 255.255.255.0, the broadcast is 192.168.1.255, there are 254 usable hosts, and the usable range runs from 192.168.1.1 to 192.168.1.254.
What are the practical limits of this tool?
It handles IPv4 only, not IPv6, and the smallest prefixes in the dropdown stop at /30, which suits point-to-point links. Remember that the network address itself and the broadcast address can never be assigned to a device, which is why usable hosts are two fewer than the total addresses.