IPv4 calculator

Subnet details, /30·/31·/32 planning, splitting, masks, private IPs, overlap check.

What it is for

Quick table of private / special IPv4 blocks used in LANs, CGNAT, link-local, etc.

Why it helps

Know the range, mask and address count — easier LAN planning and no leaking private IPs to the internet.

Private and special IPv4 blocks

RFC 1918 — main private LAN ranges. Below also other common non-public zones.

RFC 1918 (private LAN)

10.0.0.0/8

Large private / enterprise LAN

From
10.0.0.0
To
10.255.255.255
Netmask
255.0.0.0
Addresses
16777216
Usable
16777214
× /24
65536
172.16.0.0/12

Private networks (172.16–172.31)

From
172.16.0.0
To
172.31.255.255
Netmask
255.240.0.0
Addresses
1048576
Usable
1048574
× /24
4096
192.168.0.0/16

Home / small LAN (often /24)

From
192.168.0.0
To
192.168.255.255
Netmask
255.255.0.0
Addresses
65536
Usable
65534
× /24
256

Other common special blocks

Range From To Netmask Addresses Usable × /24 Use
100.64.0.0/10 100.64.0.0 100.127.255.255 255.192.0.0 4194304 4194302 16384 CGNAT / shared address space (RFC 6598)
169.254.0.0/16 169.254.0.0 169.254.255.255 255.255.0.0 65536 65534 256 Link-local APIPA (RFC 3927)
127.0.0.0/8 127.0.0.0 127.255.255.255 255.0.0.0 16777216 16777214 65536 Loopback
192.0.2.0/24 192.0.2.0 192.0.2.255 255.255.255.0 256 254 1 Documentation / examples (RFC 5737)
198.51.100.0/24 198.51.100.0 198.51.100.255 255.255.255.0 256 254 1 Documentation / examples (RFC 5737)
203.0.113.0/24 203.0.113.0 203.0.113.255 255.255.255.0 256 254 1 Documentation / examples (RFC 5737)
224.0.0.0/4 224.0.0.0 239.255.255.255 240.0.0.0 268435456 268435454 1048576 Multicast