About SubnetPad

Free subnet tools for network engineers and learners

SubnetPad is a free online subnet and CIDR calculator. Enter any IP address or prefix and get network address, broadcast, host range, subnet mask, and more — instantly, in your browser.

What we built

A fast, readable calculator with the reference material you actually need.

Subnetting is a core skill for anyone working with networks — from homelab setups and certification study to cloud VPC design and on-prem routing. Most calculators make you click a button and dump a wall of numbers. SubnetPad is designed to be the opposite: live results, plain-language labels, and educational content on the same page.

Whether you are checking a /24 for a VLAN, sizing an IPv6 /48 for a site, or learning what CIDR notation means for the first time, SubnetPad is built to help you work faster and understand more.

Features

Why use SubnetPad

Instant results

Network details update as you type. No submit button, no waiting.

Runs in your browser

Subnet calculations happen locally on your device. Your inputs are not sent to a server.

IPv4 and IPv6

Dedicated calculators for both address families, with CIDR reference pages from /0 to /32 and /0 to /128.

Built to teach

Cheat sheets, guides, and per-prefix pages help you understand subnetting — not just compute it.

Tools on this site

Jump straight to a calculator or reference page.

Get in touch

Questions, feedback, or corrections — we would like to hear from you.

SubnetPad is maintained as a free resource. If you spot an error, have a feature idea, or need to reach us for any other reason, use the contact page.