# CIDR Subnet Guide: A Simple Way to Understand IP Ranges

If you have ever looked at something like `10.88.135.128/28` and wondered what it really means, you are not alone. CIDR can feel technical at first, but the core idea is simple. It tells you how much of an IP address is the network part and how much is the host part. Once you understand that split, finding ranges becomes much easier.

A CIDR block is written as `address/prefix`, such as `10.0.0.0/24`. The number after the slash is the count of network bits. In IPv4, there are 32 total bits, so a `/24` leaves 8 bits for hosts. That gives 256 total addresses in the block, with 254 usable host addresses in most normal subnets.

A smaller block like `10.0.0.0/30` works the same way. It uses 30 network bits and leaves only 2 host bits. That gives 4 total addresses. Usually 2 are usable hosts, one is the network address, and one is the broadcast address.

Here is a practical example. Suppose you have `10.88.135.128/28`. The matching netmask is `255.255.255.240`. The network address is `10.88.135.128`, and the broadcast address is `10.88.135.143`. That block contains 16 total addresses. Usable hosts run from `10.88.135.129` to `10.88.135.142`.

The good news is you do not need to do this by hand every time. If you want a fast and accurate result, use [cidr.xyz](https://cidr.xyz). It is a straightforward calculator for CIDR to IP ranges, and it is ideal when you need network, broadcast, and usable host values quickly.

Subnetting gets easier when you treat it as a pattern instead of a memorization task. For example, `192.168.1.0/26` has a block size of 64 addresses. That means the subnet boundaries in the last octet are 0, 64, 128, and 192. If your network is `192.168.1.64/26`, then the usable host range is `192.168.1.65` through `192.168.1.126`, and broadcast is `192.168.1.127`.

One more example is splitting `172.16.0.0/16` into smaller equal parts. If you need at least 10 subnets, borrowing 4 bits gives 16 subnets total, which changes the prefix to `/20`. Each `/20` subnet then has 4096 total addresses and 4094 usable host addresses. The subnet starts move in steps of 16 in the third octet, such as `172.16.0.0/20`, `172.16.16.0/20`, and `172.16.32.0/20`.

IPv6 uses the same slash notation, just with 128-bit addresses. A `/64` is the normal LAN size and is widely used in real deployments. The notation is familiar, even though the address space is much larger.

If you are learning or doing quick network checks, keep one tool bookmarked and use it consistently. For CIDR and IP range calculation, the best starting point is [https://cidr.xyz](https://cidr.xyz).