IPv4 Subnet & IP Address Calculator
Calculate subnet mask, CIDR, network address, broadcast, usable host range and wildcard mask — and learn the major private, public and special-use IPv4 ranges.
Example: 192.168.10.25/24 equals subnet mask 255.255.255.0.
IPv4 Address Ranges: Private, Public & Special
Public IPv4 is not one single range. In general, globally routable unicast addresses are public candidates after excluding special-use, private, multicast, loopback, link-local, documentation and reserved space.
| Range | CIDR | Type / purpose | Practical meaning |
|---|---|---|---|
| 0.0.0.0 – 0.255.255.255 | 0.0.0.0/8 | Special use / “this network” | Not normal public host addressing. 0.0.0.0 also means unspecified in many contexts. |
| 10.0.0.0 – 10.255.255.255 | 10.0.0.0/8 | Private | RFC 1918; common for LAN, CCTV and enterprise networks. |
| 100.64.0.0 – 100.127.255.255 | 100.64.0.0/10 | Shared / CGNAT | Carrier-grade NAT space; not ordinary private LAN space and not globally routable public space. |
| 127.0.0.0 – 127.255.255.255 | 127.0.0.0/8 | Loopback | Traffic returns to the local host. 127.0.0.1 is the common example. |
| 169.254.0.0 – 169.254.255.255 | 169.254.0.0/16 | Link-local | Often self-assigned when DHCP cannot provide an IPv4 address. |
| 172.16.0.0 – 172.31.255.255 | 172.16.0.0/12 | Private | RFC 1918. Only 172.16–172.31 is private. |
| 192.0.0.0 – 192.0.0.255 | 192.0.0.0/24 | Special purpose | Protocol/special-purpose address space; not normal public host addressing. |
| 192.0.2.0 – 192.0.2.255 | 192.0.2.0/24 | Documentation | TEST-NET-1; use for examples and documentation. |
| 192.168.0.0 – 192.168.255.255 | 192.168.0.0/16 | Private | RFC 1918; extremely common in home, office and CCTV networks. |
| 198.18.0.0 – 198.19.255.255 | 198.18.0.0/15 | Benchmark testing | Reserved for network-device/interconnect benchmark tests. |
| 198.51.100.0 – 198.51.100.255 | 198.51.100.0/24 | Documentation | TEST-NET-2; use for examples and documentation. |
| 203.0.113.0 – 203.0.113.255 | 203.0.113.0/24 | Documentation | TEST-NET-3; use for examples and documentation. |
| 224.0.0.0 – 239.255.255.255 | 224.0.0.0/4 | Multicast | Multicast addressing, not ordinary unicast host addressing. |
| 240.0.0.0 – 255.255.255.255 | 240.0.0.0/4 | Reserved | Reserved space; not ordinary globally routable unicast. |
Classic private IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16.
Subnet Mask & CIDR Quick Reference
| CIDR | Subnet Mask | Total | Usable* |
|---|---|---|---|
| /24 | 255.255.255.0 | 256 | 254 |
| /25 | 255.255.255.128 | 128 | 126 |
| /26 | 255.255.255.192 | 64 | 62 |
| /27 | 255.255.255.224 | 32 | 30 |
| /28 | 255.255.255.240 | 16 | 14 |
| /29 | 255.255.255.248 | 8 | 6 |
| /30 | 255.255.255.252 | 4 | 2 |
*Traditional IPv4 host calculation. /31 and /32 have special uses.