Utility Tool

Subnet Calculator

Calculate clean IPv4 and IPv6 subnet details without the weird old page. This first-pass standalone tool gives you the basics now so Phase 2 can build on a solid surface.

Calculator Examples Guide

Calculator

Results

Enter a CIDR to see the calculated summary.

Examples

Learn more

How to use the Subnet CalculatorRead the guide inside WhenIP Academy. What is CIDR and subnetting?Get the basics before you trust the numbers. Private IP rangesRefresh the RFC1918 space quickly. Reserved IP rangesUnderstand non-routable and special-use space.