CIDR Subnet Calculator
Calculate IPv4 CIDR ranges instantly: network address, broadcast, host range, subnet mask, wildcard, and total hosts. Perfect for VPC planning, firewall rules, and network design.
Network address
192.168.1.0
Broadcast address
192.168.1.255
First usable host
192.168.1.1
Last usable host
192.168.1.254
Subnet mask
255.255.255.0
Wildcard mask
0.0.0.255
Total addresses
256
Usable hosts
254
CIDR notation
192.168.1.0/24
Address class
C · Private (RFC 1918)
Binary layout
Blue bits are the network portion (first 24), gray bits are the host portion.
CIDR in one minute
Classless Inter-Domain Routing (CIDR) replaced the old Class A/B/C addressing scheme. A CIDR block is written asIP/N, where N is the number of leading network bits. The remaining 32 − Nbits identify hosts inside that network.
The smaller the prefix, the bigger the block. /24 holds 256 addresses;/16 holds 65,536. /32 is a single host. Each step up doubles the size of the range.
Common prefix sizes
| CIDR | Subnet mask | Addresses | Usable hosts |
|---|---|---|---|
| /30 | 255.255.255.252 | 4 | 2 |
| /29 | 255.255.255.248 | 8 | 6 |
| /28 | 255.255.255.240 | 16 | 14 |
| /24 | 255.255.255.0 | 256 | 254 |
| /20 | 255.255.240.0 | 4,096 | 4,094 |
| /16 | 255.255.0.0 | 65,536 | 65,534 |
| /8 | 255.0.0.0 | 16,777,216 | 16,777,214 |
Usable hosts excludes the network address and broadcast address, except in /31 and/32 point-to-point cases (RFC 3021).
Private IP ranges (RFC 1918)
- 10.0.0.0/8 — 16,777,216 addresses
- 172.16.0.0/12 — 1,048,576 addresses
- 192.168.0.0/16 — 65,536 addresses
These ranges are reserved for private networks and never routed on the public internet.