IP Subnet Calculator
Full IPv4 subnet report from any IP + netmask or prefix — including binary and hex representations.
This tool runs 100% in your browser. Your data is never uploaded, stored, or logged.
Subnet report
Enter an IP and netmask to get the full subnet report, including binary and hex forms.
About this tool
Give it an IP and a mask — as dotted decimal (255.255.255.0) or prefix (/24) — and get the complete subnet picture: network, broadcast, usable range, host counts, wildcard mask, IP classification, plus binary and hexadecimal forms for the bit-level view.
Non-contiguous masks are rejected with a clear explanation, catching a classic configuration typo.
How to use it
- Enter the IP address (e.g.
10.0.5.20). - Enter the netmask as dotted decimal or a /prefix.
- Read the full report, including binary IP and netmask.
- Copy values into your network documentation.
Useful ways to apply it
- Configuring static IPs with the right mask and gateway range.
- Verifying VLAN subnet boundaries.
- Studying for networking certifications (binary view included).
- Diagnosing "same subnet?" connectivity questions.
Frequently asked questions
Dotted mask or prefix — which should I enter?
Either. 255.255.255.0 and /24 are identical; the calculator accepts both and shows the other form in the report.
What is a non-contiguous mask?
A mask whose binary form mixes 1s after 0s (like 255.0.255.0). These are invalid for subnetting and the calculator rejects them explicitly.
IPv6 support?
This tool is IPv4-only for now.
Privacy
This tool runs 100% in your browser. Your data is never uploaded, stored, or logged.