CIDR Calculator
Calculate CIDR notation, subnet masks, network addresses, and IP ranges for network planning.
CIDR Notation
Common Subnet Sizes
| CIDR | Usable Hosts | Note |
|---|---|---|
| /8 | 16,777,214 | Class A |
| /16 | 65,534 | Class B |
| /24 | 254 | Class C |
| /25 | 126 | |
| /26 | 62 | |
| /27 | 30 | |
| /28 | 14 | |
| /29 | 6 | |
| /30 | 2 | Point-to-point |
| /32 | 1 | Host route |
Features
CIDR Notation
Support for all CIDR prefixes /0 to /32
IP Range
Calculate first and last usable hosts
Instant Calculation
Results update immediately
Quick Reference
Common subnet size table