Subnet Mask Cheat Sheet
Every IPv4 prefix with its mask and host count, next to a calculator.
IPv4 or IPv6; a prefix or mask typed after the address wins.
IPv4 Subnet Mask and CIDR Table
The table lists every prefix length with its mask. The Subnet Calculator above does the same for any address you type, including the network, broadcast and host range.
| Prefix | Subnet mask | Wildcard | Addresses | Usable hosts |
|---|---|---|---|---|
| /32 | 255.255.255.255 | 0.0.0.0 | 1 | 1 |
| /31 | 255.255.255.254 | 0.0.0.1 | 2 | 2 |
| /30 | 255.255.255.252 | 0.0.0.3 | 4 | 2 |
| /29 | 255.255.255.248 | 0.0.0.7 | 8 | 6 |
| /28 | 255.255.255.240 | 0.0.0.15 | 16 | 14 |
| /27 | 255.255.255.224 | 0.0.0.31 | 32 | 30 |
| /26 | 255.255.255.192 | 0.0.0.63 | 64 | 62 |
| /25 | 255.255.255.128 | 0.0.0.127 | 128 | 126 |
| /24 | 255.255.255.0 | 0.0.0.255 | 256 | 254 |
| /23 | 255.255.254.0 | 0.0.1.255 | 512 | 510 |
| /22 | 255.255.252.0 | 0.0.3.255 | 1,024 | 1,022 |
| /21 | 255.255.248.0 | 0.0.7.255 | 2,048 | 2,046 |
| /20 | 255.255.240.0 | 0.0.15.255 | 4,096 | 4,094 |
| /19 | 255.255.224.0 | 0.0.31.255 | 8,192 | 8,190 |
| /18 | 255.255.192.0 | 0.0.63.255 | 16,384 | 16,382 |
| /17 | 255.255.128.0 | 0.0.127.255 | 32,768 | 32,766 |
| /16 | 255.255.0.0 | 0.0.255.255 | 65,536 | 65,534 |
| /15 | 255.254.0.0 | 0.1.255.255 | 131,072 | 131,070 |
| /14 | 255.252.0.0 | 0.3.255.255 | 262,144 | 262,142 |
| /13 | 255.248.0.0 | 0.7.255.255 | 524,288 | 524,286 |
| /12 | 255.240.0.0 | 0.15.255.255 | 1,048,576 | 1,048,574 |
| /11 | 255.224.0.0 | 0.31.255.255 | 2,097,152 | 2,097,150 |
| /10 | 255.192.0.0 | 0.63.255.255 | 4,194,304 | 4,194,302 |
| /9 | 255.128.0.0 | 0.127.255.255 | 8,388,608 | 8,388,606 |
| /8 | 255.0.0.0 | 0.255.255.255 | 16,777,216 | 16,777,214 |
| /7 | 254.0.0.0 | 1.255.255.255 | 33,554,432 | 33,554,430 |
| /6 | 252.0.0.0 | 3.255.255.255 | 67,108,864 | 67,108,862 |
| /5 | 248.0.0.0 | 7.255.255.255 | 134,217,728 | 134,217,726 |
| /4 | 240.0.0.0 | 15.255.255.255 | 268,435,456 | 268,435,454 |
| /3 | 224.0.0.0 | 31.255.255.255 | 536,870,912 | 536,870,910 |
| /2 | 192.0.0.0 | 63.255.255.255 | 1,073,741,824 | 1,073,741,822 |
| /1 | 128.0.0.0 | 127.255.255.255 | 2,147,483,648 | 2,147,483,646 |
| /0 | 0.0.0.0 | 255.255.255.255 | 4,294,967,296 | 4,294,967,294 |
The only numbers a mask can contain
Each part of a subnet mask is one of nine values: 0, 128, 192, 224, 240, 248, 252, 254 or 255, because the ones in a mask must all come first. A mask such as 255.255.255.100 is invalid, and the calculator says so.
Related tools
To see the range a block covers, use CIDR to IP range. For IPv6, see the IPv6 subnet calculator.