CIDR Aggregation Calculator
Calculate CIDR notation, find the smallest supernet containing multiple networks, and plan route aggregation for BGP and routing tables.
About CIDR Aggregation
CIDR (Classless Inter-Domain Routing) aggregation combines multiple contiguous networks into a single, larger network (supernet). This reduces the size of routing tables and improves routing efficiency, especially in BGP.
Common CIDR Aggregation Examples
| Networks | Aggregated CIDR | Address Range |
|---|---|---|
| 192.168.0.0/24 + 192.168.1.0/24 | 192.168.0.0/23 | 192.168.0.0 - 192.168.1.255 |
| 192.168.0.0/24 + 192.168.1.0/24 + 192.168.2.0/24 + 192.168.3.0/24 | 192.168.0.0/22 | 192.168.0.0 - 192.168.3.255 |
| 10.0.0.0/24 + 10.0.1.0/24 + ... + 10.0.15.0/24 | 10.0.0.0/20 | 10.0.0.0 - 10.0.15.255 |
| 172.16.0.0/24 + 172.16.1.0/24 + 172.16.2.0/24 + 172.16.3.0/24 | 172.16.0.0/22 | 172.16.0.0 - 172.16.3.255 |
CIDR Cheat Sheet
| CIDR | Subnet Mask | # IPs | # Usable | Typical Use |
|---|---|---|---|---|
| /32 | 255.255.255.255 | 1 | 1 | Host route |
| /31 | 255.255.255.254 | 2 | 2 | Point-to-point |
| /30 | 255.255.255.252 | 4 | 2 | Point-to-point |
| /29 | 255.255.255.248 | 8 | 6 | Small network |
| /28 | 255.255.255.240 | 16 | 14 | Small network |
| /27 | 255.255.255.224 | 32 | 30 | Small office |
| /26 | 255.255.255.192 | 64 | 62 | Office network |
| /25 | 255.255.255.128 | 128 | 126 | Medium office |
| /24 | 255.255.255.0 | 256 | 254 | Typical LAN |
| /23 | 255.255.254.0 | 512 | 510 | Larger network |
| /22 | 255.255.252.0 | 1024 | 1022 | Data center |
| /21 | 255.255.248.0 | 2048 | 2046 | Large org |
| /20 | 255.255.240.0 | 4096 | 4094 | Large org |