IP Subnet & CIDR Calculator
Calculate network, broadcast, host range and subnet mask from an IPv4 CIDR — 100% in your browser.
IPv4. A prefix defaults to /24 if you omit it.
About IP Subnet & CIDR Calculator
Enter an IPv4 address with a CIDR prefix (like 192.168.1.0/24) and instantly see the network address, broadcast address, first and last usable host, total and usable host counts, the subnet and wildcard masks, the address class and whether the range is private or public.
It's handy for planning subnets and debugging network configs. All math is done locally in your browser; nothing is sent anywhere.
How to use IP / CIDR Calculator
- Enter an IPv4 address with a CIDR prefix, then inspect the mask, network, broadcast and range.
- Compare the result with the network plan and routing rules you intend to configure.
Limitations and common mistakes
A /24 contains 256 addresses, but usable-host conventions differ for /31 point-to-point and /32 host routes. Do not subtract two blindly from every prefix.
This tool calculates IPv4 ranges; it does not scan devices or validate your routing configuration. Use the IPv4-to-IPv6 tool for mapped-address notation.
The tool processes its input locally on your device. Read our privacy policy for analytics, storage and network details.
A /24 network
192.168.1.10/24
network 192.168.1.0 · broadcast 192.168.1.255 · 254 usable hosts
Omit the prefix and it defaults to /24; works for any prefix 0–32.
Frequently asked questions
What's the difference between the network and broadcast address?
The network address is the first address in the block (all host bits 0) and identifies the subnet; the broadcast address is the last (all host bits 1) and reaches every host. Neither is usually assigned to a host.
Why are usable hosts two fewer than the total?
The network and broadcast addresses are reserved, so a /24 has 256 total addresses but 254 usable. (/31 and /32 are special cases used for point-to-point links and single hosts.)
What is a wildcard mask?
It's the bitwise inverse of the subnet mask (e.g. 0.0.0.255 for /24), used by some routers and ACLs to match a range of addresses.
Does it support IPv6?
Not yet — this calculator handles IPv4 addresses and prefixes from 0 to 32.
For related tasks, explore HTTP Status Codes and Number Base Converter. Their guides explain the different inputs, assumptions and output formats.