IPv4 reference
CIDR subnet chart from /0 to /32
Use one complete reference table for every IPv4 prefix, dotted-decimal mask, total addresses, and usable-address rule.
Private browser calculation
Address, prefix, and host sizing
Complete finite reference
All 33 IPv4 CIDR prefixes
Usable counts reserve network and broadcast for /0 through /30. /31 follows point-to-point semantics and /32 names one host route.
| CIDR | Subnet mask | Total addresses | Usable addresses | Interpretation |
|---|---|---|---|---|
| /0 | 0.0.0.0 | 4294967296 | 4294967294 | Ordinary subnet |
| /1 | 128.0.0.0 | 2147483648 | 2147483646 | Ordinary subnet |
| /2 | 192.0.0.0 | 1073741824 | 1073741822 | Ordinary subnet |
| /3 | 224.0.0.0 | 536870912 | 536870910 | Ordinary subnet |
| /4 | 240.0.0.0 | 268435456 | 268435454 | Ordinary subnet |
| /5 | 248.0.0.0 | 134217728 | 134217726 | Ordinary subnet |
| /6 | 252.0.0.0 | 67108864 | 67108862 | Ordinary subnet |
| /7 | 254.0.0.0 | 33554432 | 33554430 | Ordinary subnet |
| /8 | 255.0.0.0 | 16777216 | 16777214 | Ordinary subnet |
| /9 | 255.128.0.0 | 8388608 | 8388606 | Ordinary subnet |
| /10 | 255.192.0.0 | 4194304 | 4194302 | Ordinary subnet |
| /11 | 255.224.0.0 | 2097152 | 2097150 | Ordinary subnet |
| /12 | 255.240.0.0 | 1048576 | 1048574 | Ordinary subnet |
| /13 | 255.248.0.0 | 524288 | 524286 | Ordinary subnet |
| /14 | 255.252.0.0 | 262144 | 262142 | Ordinary subnet |
| /15 | 255.254.0.0 | 131072 | 131070 | Ordinary subnet |
| /16 | 255.255.0.0 | 65536 | 65534 | Ordinary subnet |
| /17 | 255.255.128.0 | 32768 | 32766 | Ordinary subnet |
| /18 | 255.255.192.0 | 16384 | 16382 | Ordinary subnet |
| /19 | 255.255.224.0 | 8192 | 8190 | Ordinary subnet |
| /20 | 255.255.240.0 | 4096 | 4094 | Ordinary subnet |
| /21 | 255.255.248.0 | 2048 | 2046 | Ordinary subnet |
| /22 | 255.255.252.0 | 1024 | 1022 | Ordinary subnet |
| /23 | 255.255.254.0 | 512 | 510 | Ordinary subnet |
| /24 | 255.255.255.0 | 256 | 254 | Ordinary subnet |
| /25 | 255.255.255.128 | 128 | 126 | Ordinary subnet |
| /26 | 255.255.255.192 | 64 | 62 | Ordinary subnet |
| /27 | 255.255.255.224 | 32 | 30 | Ordinary subnet |
| /28 | 255.255.255.240 | 16 | 14 | Ordinary subnet |
| /29 | 255.255.255.248 | 8 | 6 | Ordinary subnet |
| /30 | 255.255.255.252 | 4 | 2 | Ordinary subnet |
| /31 | 255.255.255.254 | 2 | 2 | RFC 3021 point-to-point /31 |
| /32 | 255.255.255.255 | 1 | 1 | Single host route /32 |