IPv4 / Subnet Calculator
Calculate network, broadcast, host range and mask from an IPv4 address and CIDR prefix.
What this tool does
Enter an IPv4 address and CIDR prefix to calculate the network address, subnet mask, broadcast address and usable host range. It is a planning aid for checking a configuration; confirm the intended subnet and routing rules before changing a live network.
How to use it
Enter the values requested by the calculator and check the result together with the notes shown below it.
Practical example
Use a realistic example from your own setup to compare scenarios. The result is a reference, not a replacement for manufacturer specifications.
How to interpret the result
Treat the result as an estimate whenever real-world factors are not available to the browser. For hardware, network or safety decisions, verify the relevant technical specifications.
Frequently asked questions
What does /24 mean?
That the first 24 bits identify the network and 8 bits remain for hosts: mask 255.255.255.0 and 254 usable hosts.
Why are two addresses subtracted?
The first is the network address and the last is the broadcast; neither can be assigned to a device.