IP Subnet Calculator
IP Subnet Calculator
Overview
Use this IP subnet calculator to turn CIDR notation into network details you can actually use. It helps with IPv4 subnet masks, usable host ranges, wildcard masks, broadcast addresses, and IPv6 prefix planning for firewall rules, VLAN design, static addressing, home labs, certification study, and quick troubleshooting.
About
About IP Subnet Calculator
Subnetting is easy to get wrong when you are switching between slash notation, dotted masks, host counts, and real-world range checks. A focused subnet calculator reduces manual mistakes and speeds up network planning.
Features:
- Convert IPv4 CIDR notation into subnet mask, wildcard mask, network, broadcast, and usable host range
- See total addresses, usable hosts, and binary octets for quick verification
- Summarize IPv6 prefixes with compressed and expanded network forms plus host-bit counts
- Useful for VLAN design, ACLs, firewall rules, DHCP pools, and certification study
- Copy key results quickly without spreadsheet math or manual bit counting
- Runs instantly in your browser with no sign-in
What strong subnet planning usually requires
The most useful subnet tools do more than convert /24 to 255.255.255.0. They help you verify where a network starts, which host addresses are usable, what broadcast or wildcard values apply, and how much address space remains for growth so implementation mistakes do not slip into production changes.
FAQ
What is CIDR notation?
CIDR notation is the slash form like /24 or /64 that tells you how many leading bits belong to the network portion of the address.
What is the wildcard mask used for?
A wildcard mask is the inverse of the subnet mask. It is often used in ACLs and network-matching rules where you need to describe which bits can vary.
Why does a /31 or /32 show zero usable hosts here?
This calculator uses the traditional host-count model where network and broadcast addresses are reserved. Some special point-to-point designs treat /31 differently, but that is a deployment-specific exception.
Does IPv6 have broadcast addresses?
No. IPv6 does not use broadcast addresses the way IPv4 does. IPv6 subnet planning is usually centered on the network prefix, prefix length, and the size of the host space.
When would I use this instead of What Is My IP?
What Is My IP tells you about your current public connection. This subnet calculator helps you design or verify network ranges, masks, and prefixes for internal or planned addressing.