IP Subnet Calculator
IP Subnet Calculator turns an IPv4 address and prefix into everything you need for network planning: network and broadcast addresses, the usable host range and counts, dotted and binary subnet masks, the wildcard mask, and the address class and scope.
Last updated: July 2026
A subnet calculator takes an IPv4 address and CIDR prefix (like 192.168.1.0/24) and derives the network and broadcast addresses, the first and last usable hosts, total and usable host counts, the subnet and wildcard masks and the IP class — including whether the address is private or public — instantly in your browser.
How to use IP Subnet Calculator
- Enter an IPv4 address — pasting CIDR form like 10.0.0.0/8 works too.
- Pick the CIDR prefix / subnet mask if you didn't use the slash form.
- Read the network, broadcast, host range, masks and IP class instantly.
Frequently asked questions
How are usable hosts counted?
For prefixes up to /30 it's total hosts minus the network and broadcast addresses. A /31 point-to-point link has 2 usable addresses (RFC 3021) and a /32 is a single host.
How does it tell private from public?
It checks the RFC 1918 ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), plus loopback and link-local, and labels everything else public.
Is my network data uploaded?
No. All subnet math runs locally in your browser — addresses you enter are never sent to a server.
Related developer tools
Number Base Converter
Convert numbers between binary, octal, decimal and hexadecimal instantly. Free in-browser hex-to-decimal and base converter.
Text to Binary Converter
Convert text to binary and binary back to text (UTF-8). Free, instant, in-browser text-to-binary converter.
HTTP Status Codes
Look up any HTTP status code (200, 301, 404, 500…) with its meaning and category. Free, instant, searchable reference.
UUID Generator
Generate random v4 UUIDs (GUIDs) in bulk and copy them with one click. Free, instant and fully in-browser using the secure crypto API.