How Many IP Addresses Are in a Block?

What Is an IP Block?

An IP block is simply a group of IP addresses.
Think of it like a batch of phone numbers assigned to a business or building — each device in a network needs its own IP, and an IP block provides that.

Example:
192.168.1.0/24 is an IP block. The /24 part tells us how many IP addresses it includes.

What Does /24, /30, etc. Mean?

This is called CIDR notation. It indicates how many bits are fixed for the network and how many are available for hosts (usable IPs).

Here’s the quick formula:

Total IPs = 2^(32 - CIDR)

Examples:

• /24 → 2^(32–24) = 256 total IPs
• /30 → 2^(32–30) = 4 total IPs

But not all IPs are usable.

Two IPs in every block are reserved:

• One is the network address (the first one)
• One is the broadcast address (the last one)

So, usable IPs = total IPs – 2

Quick IP Block Reference Table

Which IP Block Should You Use?

It depends on how many devices (hosts) you need to assign IPs to:

• Need 2 devices? Use /30
• Need around 50 IPs? Use /26
• Need around 250 IPs? /24 works well

Not a Fan of Math? Use Our IP Block Calculator

To make your life easier, we’ve created a simple IP calculator.

You just enter the CIDR block (like /27), and it will tell you:

• Total number of IPs
• Usable IPs
• Network and broadcast addresses

Use the calculator here:
Click to Open the Simple IP Calculator

No formulas. No guesswork. Just instant answers.

Final Thoughts

Knowing how many IP addresses are in a block is easier than it seems.
You can either:

• Use the formula 2^(32 - CIDR) and subtract 2
• Or simply use the calculator above

Once you get the hang of it, you’ll never be confused by IP ranges again.