IPv4 Subnetting & CIDR Notation Guide: Cheat Sheet & Calculations
Understand Classless Inter-Domain Routing (CIDR), subnet masks, network addresses, broadcast IPs, and usable host formulas with a complete cheat sheet.
September 2, 2026
11 min read
Demystifying IP Addressing and Subnetting
🌐 Calculate Subnets & IP Ranges
Calculate network ID, broadcast addresses, wildcard masks, and binary notation with our CIDR & IPv4 Subnet Calculator.
Subnetting is the practice of dividing a large IP network into smaller, logically isolated network segments (subnets) to improve network routing efficiency, enhance security, and conserve IP address space.
1. CIDR Prefix Cheat Sheet (/24 to /30)
| CIDR Prefix | Subnet Mask | Total Addresses | Usable Host IPs |
|---|---|---|---|
| /24 | 255.255.255.0 | 256 | 254 |
| /26 | 255.255.255.192 | 64 | 62 |
| /28 | 255.255.255.240 | 16 | 14 |
| /30 | 255.255.255.252 | 4 | 2 (Point-to-Point) |