IP & Subnet Calculator
Calculate IP ranges, subnet details, and generate usable IP lists
Network Input
Enter an IPv4 address with CIDR or subnet mask
Quick Examples
One click fillCIDR ↔ Subnet Reference
Common masksQuick Guide
Ready to Calculate
Enter an IPv4 address and subnet details to view network address, broadcast, usable hosts, wildcard mask, and address list.
Network Summary
Core subnet information
Address Breakdown
Special values and binary-friendly details
Address List
Generated from resolver output
Resolve Steps
Learn more & FAQ
What does an IP subnet calculator do?
Networks are carved up into subnets using CIDR notation (an address plus a prefix length, like 10.0.0.0/24). This tool takes that notation and works out everything derived from it: the network address, broadcast address, subnet mask, and the full range of usable host addresses - the arithmetic you'd otherwise have to do in binary by hand.
How to read your results
Enter an address and prefix length (or a subnet mask) and the calculator breaks down the network and broadcast addresses, the usable host range, and the total vs. usable address counts. The IP list shows every address in range for smaller subnets, and the resolve steps walk through how each value was derived - useful when you need to explain a subnet plan to someone else, not just get the answer.
Frequently asked questions
What does a CIDR like /24 actually mean?
The number after the slash is how many bits of the address are fixed as the network portion - the rest are available for hosts. A /24 fixes the first 24 bits, leaving 8 bits (256 addresses) for hosts, which is why /24 is the classic 256-address subnet.
Why is the usable host count smaller than the total addresses in a subnet?
Every IPv4 subnet reserves its first address as the network address and its last as the broadcast address, so a /24's 256 total addresses give you 254 usable host addresses.
What's the difference between a subnet mask and CIDR notation?
They describe the same thing two ways: a subnet mask (like 255.255.255.0) and CIDR notation (like /24) both mark where the network portion of an address ends. This tool converts between the two automatically.
How do I split a larger block into smaller subnets?
Increasing the prefix length (e.g. going from /24 to /25) halves the address space into two equal subnets each time. Enter your base CIDR block and the calculator shows the resulting network, broadcast, and usable range so you can plan the split.
Does this work for IPv6 subnets too?
Yes - enter an IPv6 address with a prefix length (e.g. 2001:db8::/32) and the calculator resolves the network range the same way it does for IPv4.