CIDR Calculator
Calculate a subnet's network address, broadcast address, mask, and usable host range — plus quick-reference tables for private, reserved, and special IP ranges.
Calculator
- Network address
- Broadcast address
- Subnet mask
- Wildcard mask
- Usable host range
- Usable hosts
- Total addresses
- Classification
Common prefix lengths
| Prefix | Subnet mask | Total addresses | Usable hosts |
|---|---|---|---|
| /30 | 255.255.255.252 | 4 | 2 |
| /29 | 255.255.255.248 | 8 | 6 |
| /28 | 255.255.255.240 | 16 | 14 |
| /27 | 255.255.255.224 | 32 | 30 |
| /26 | 255.255.255.192 | 64 | 62 |
| /25 | 255.255.255.128 | 128 | 126 |
| /24 | 255.255.255.0 | 256 | 254 |
| /23 | 255.255.254.0 | 512 | 510 |
| /22 | 255.255.252.0 | 1,024 | 1,022 |
| /21 | 255.255.248.0 | 2,048 | 2,046 |
| /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 |
Private & reserved IPv4 ranges
| Range | Purpose |
|---|---|
| 10.0.0.0/8 | Private — RFC 1918 |
| 172.16.0.0/12 | Private — RFC 1918 |
| 192.168.0.0/16 | Private — RFC 1918 |
| 100.64.0.0/10 | Carrier-grade NAT — RFC 6598 |
| 127.0.0.0/8 | Loopback |
| 169.254.0.0/16 | Link-local (APIPA) |
| 192.0.0.0/24 | IETF protocol assignments |
| 192.0.2.0/24 | Documentation (TEST-NET-1) |
| 198.51.100.0/24 | Documentation (TEST-NET-2) |
| 203.0.113.0/24 | Documentation (TEST-NET-3) |
| 198.18.0.0/15 | Benchmark testing |
| 224.0.0.0/4 | Multicast |
| 240.0.0.0/4 | Reserved for future use |
| 255.255.255.255/32 | Limited broadcast |
Special IPv6 ranges
| Range | Purpose |
|---|---|
| ::/128 | Unspecified address |
| ::1/128 | Loopback |
| fc00::/7 | Unique local — private, RFC 4193 |
| fe80::/10 | Link-local |
| ::ffff:0:0/96 | IPv4-mapped address |
| 64:ff9b::/96 | NAT64 |
| 2001:db8::/32 | Documentation |
| 2002::/16 | 6to4 (deprecated) |
| ff00::/8 | Multicast |
| 2000::/3 | Global unicast — public |