Subnet Cheat Sheet

What is Subnet Cheat Sheet?

A compact, practical reference for IPv4 subnetting and CIDR math. It combines a CIDR lookup table, quick formulas, and small calculators so network admins can find subnet masks, usable hosts, wildcard masks, and private ranges fast. The page explains classful/ classless addressing, the /31 point-to-point exception, and common masks used in network design. Use it to check ranges, convert between representations, or plan subnets without digging through long documentation.

Key features

• Calculate CIDR prefixes, subnet masks, and address counts quickly.
• Lookup IP addresses and determine private or public ranges instantly.
• Show wildcard masks and host bits for access control lists.
• Support special cases such as 31-bit point-to-point links accurately.
• Provide VLSM tools and conversions between IPv4 and IPv6.
• Include classful ranges, formulas, and a printable cheat table.