Quick reference crib sheet for daily subnetting tasks.
You can use the IPv4 and IPv6 charts for IP address planning and to convert subnet masks to CIDR and wildcards.
| CIDR | Subnet | # Addresses | Wildcard |
|---|---|---|---|
| /32 | 255.255.255.255 | 1 | 0.0.0.0 |
| /31 | 255.255.255.254 | 2 | 0.0.0.1 |
| /30 | 255.255.255.252 | 4 | 0.0.0.3 |
| /29 | 255.255.255.248 | 8 | 0.0.0.7 |
| /28 | 255.255.255.240 | 16 | 0.0.0.15 |
| /27 | 255.255.255.224 | 32 | 0.0.0.31 |
| /26 | 255.255.255.192 | 64 | 0.0.0.63 |
| /25 | 255.255.255.128 | 128 | 0.0.0.127 |
| /24 | 255.255.255.0 | 256 | 0.0.0.255 |
| /23 | 255.255.254.0 | 512 | 0.0.1.255 |
| /22 | 255.255.252.0 | 1024 | 0.0.3.255 |
| /21 | 255.255.248.0 | 2048 | 0.0.7.255 |
| /20 | 255.255.240.0 | 4096 | 0.0.15.255 |
| /19 | 255.255.224.0 | 8192 | 0.0.31.255 |
| /18 | 255.255.192.0 | 16,384 | 0.0.63.255 |
| /17 | 255.255.128.0 | 32,768 | 0.0.127.255 |
| /16 | 255.255.0.0 | 65,536 | 0.0.255.255 |
| /15 | 255.254.0.0 | 131,072 | 0.1.255.255 |
| /14 | 255.252.0.0 | 262,144 | 0.3.255.255 |
| /13 | 255.248.0.0 | 524,288 | 0.7.255.255 |
| /12 | 255.240.0.0 | 1,048,576 | 0.15.255.255 |
| /11 | 255.224.0.0 | 2,097,152 | 0.31.255.255 |
| /10 | 255.192.0.0 | 4,194,304 | 0.63.255.255 |
| /9 | 255.128.0.0 | 8,388,608 | 0.127.255.255 |
| /8 | 255.0.0.0 | 16,777,216 | 0.255.255.255 |
| Prefix | /48 | /56 | /64 | /127 | # Addresses |
|---|---|---|---|---|---|
| /24 | 16M | 4G | 1T | 8388608Y | 16777216Y |
| /25 | 8M | 2G | 512G | 4194304Y | 8388608Y |
| /26 | 4M | 1G | 256G | 2097152Y | 4194304Y |
| /27 | 2M | 512M | 128G | 1048576Y | 2097152Y |
| /28 | 1M | 256M | 64G | 524288Y | 1048576Y |
| /29 | 512K | 128M | 32G | 262144Y | 524288Y |
| /30 | 256K | 64M | 16G | 131072Y | 262144Y |
| /31 | 128K | 32M | 8G | 65536Y | 131072Y |
| /32 | 64K | 16M | 4G | 32768Y | 65536Y |
| /33 | 32K | 8M | 2G | 16384Y | 32768Y |
| /34 | 16K | 4M | 1G | 8192Y | 16384Y |
| /35 | 8K | 2M | 512M | 4096Y | 8192Y |
| /36 | 4K | 1M | 256M | 2048Y | 4096Y |
| /37 | 2K | 512K | 128M | 1024Y | 2048Y |
| /38 | 1K | 256K | 64M | 512Y | 1024Y |
| /39 | 512 | 128K | 32M | 256Y | 512Y |
| /40 | 256 | 64K | 16M | 128Y | 256Y |
| /41 | 128 | 32K | 8M | 64Y | 128Y |
| /42 | 64 | 16K | 4M | 32Y | 64Y |
| /43 | 32 | 8K | 2M | 16Y | 32Y |
| /44 | 16 | 4K | 1M | 8Y | 16Y |
| /45 | 8 | 2K | 512K | 4Y | 8Y |
| /46 | 4 | 1K | 256K | 2Y | 4Y |
| /47 | 2 | 512 | 128K | 1Y | 2Y |
| /48 | 1 | 256 | 64K | 512Z | 1Y |
| /49 | 128 | 32K | 256Z | 512Z | |
| /50 | 64 | 16K | 128Z | 256Z | |
| /51 | 32 | 8K | 64Z | 128Z | |
| /52 | 16 | 4K | 32Z | 64Z | |
| /53 | 8 | 2K | 16Z | 32Z | |
| /54 | 4 | 1K | 8Z | 16Z | |
| /55 | 2 | 512 | 4Z | 8Z | |
| /56 | 1 | 256 | 2Z | 4Z | |
| /57 | 128 | 1Z | 2Z | ||
| /58 | 64 | 512E | 1Z | ||
| /59 | 32 | 256E | 512E | ||
| /60 | 16 | 128E | 256E | ||
| /61 | 8 | 64E | 128E | ||
| /62 | 4 | 32E | 64E | ||
| /63 | 2 | 16E | 32E | ||
| /64 | 1 | 8E | 16E |
The subnet mask cheat sheet units is based on IEC 60027-2: Y = 1,208,925,819,614,629,174,706,176; Z = 1,180,591,620,717,411,303,424; E = 1,152,921,504,606,846,976; T = 1,099,511,627,776; G = 1,073,741,824; M = 1,048,576; K = 1,024
