IP Cheat Chart
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IP Cheat Chart
The IP Cheat Chart gives IT administrators a fast, reliable reference for CIDR slash ranges, making it easy to identify how many IP addresses exist within each subnet. For example, a /24 network contains 256 total IP addresses, though 3 are typically reserved within each defined range.
CIDR (Classless Inter‑Domain Routing) is a modern method for allocating and routing IP addresses more efficiently than traditional class‑based networking. By replacing the old Class A, B, and C structure, CIDR significantly expands the number of usable Internet addresses and is now the standard routing system across the Internet backbone.
CIDR also benefits small businesses by allowing multiple Class C networks—such as four /24 blocks—to be combined into a single larger subnet, providing more than 1,000 usable IP addresses.
Here is a quick reference IP numbering chart:
| Network Type | Sub-net Mask | Number of IPs |
| / 0 | 0.0.0.0 | 4 billion |
| / 1 | 128.0.0.0 | 2 billion |
| / 2 | 192.0.0.0 | 1billion |
| / 3 | 224.0.0.0 | 500 million |
| / 4 | 240.0.0.0 | 250 million |
| / 5 | 248.0.0.0 | 128 million |
| / 6 | 252.0.0.0 | 64 million |
| / 7 | 254.0.0.0 | 32 million |
| / 8 | 255.0.0.0 | 16 million |
| / 9 | 255.128.0.0 | 8 million |
| / 10 | 255.192.0.0 | 4 million |
| / 11 | 255.224.0.0 | 2 million |
| / 12 | 255.240.0.0 | 1 million |
| / 13 | 255.248.0.0 | 524288 |
| / 14 | 255.252.0.0 | 262144 |
| / 15 | 255.254.0.0 | 131072 |
| / 16 | 255.255.0.0 | 65536 |
| / 17 | 255.255.128.0 | 32768 |
| / 18 | 255.255.192.0 | 16384 |
| / 19 | 255.255.224.0 | 8192 |
| / 20 | 255.255.240.0 | 4096 |
| / 21 | 255.255.248.0 | 2048 |
| / 22 | 255.255.252.0 | 1024 |
| / 23 | 255.255.254.0 | 512 |
| / 24 | 255.255.255.0 | 256 |
| / 25 | 255.255.255.128 | 128 |
| / 26 | 255.255.255.192 | 64 |
| / 27 | 255.255.255.224 | 32 |
| / 28 | 255.255.255.240 | 16 |
| / 29 | 255.255.255.248 | 8 |
| / 30 | 255.255.255.252 | 4 |
| / 31 | 255.255.255.254 | 2 |
| / 32 | 255.255.255.255 | 1 |
The first few on the list would be very difficult to manage networks, and the last two are meaningless subnet masks, which would serve no purpose since the only two IP addresses available are taken by the network number and broadcast address.
