IP Subnet Calculator

An IP subnet calculator helps you plan and manage an IP network. It finds the network address, subnet mask, broadcast address, and usable host range. You don't need to work through long binary math by hand.

We developed this IP Subnet Calculator so you can get fast, clear, and accurate results. It's useful for network admins, IT students, web hosts, and small business teams.

Think of a network like a large building. Subnets split it into smaller rooms. Each room has its own range of IP addresses.

What Is an IP Subnet?

An IP subnet is a small part of a larger IP network. It helps divide devices into groups. This can make network planning and IP address use easier.

IPv4 addresses have 32 bits. A CIDR prefix, such as /24, tells you how many bits belong to the network. The rest can identify hosts within that subnet.

IP Subnet Calculator Formula

These core formulas help you find key IPv4 subnet details.

Host bits = 32 − CIDR prefix

Total IP addresses = 2 ^ host bits

Usable hosts = Total IP addresses − 2

Subnet mask = The first CIDR prefix bits set to 1

Network address = IP address AND subnet mask

Wildcard mask = 255.255.255.255 − subnet mask

Broadcast address = Network address OR wildcard mask

For normal IPv4 subnets from /0 to /30, the usable host count excludes the network and broadcast addresses. A /31 can support two addresses on a point-to-point link. A /32 represents one IP address.

How to Use the Online IP Subnet Calculator

Enter an IPv4 address. For example, use 192.168.10.77.

1. Enter the CIDR prefix. Choose /26 or enter a valid subnet mask.
2. Click Calculate. The tool checks your input and runs the subnet math.
3. Review the results. Check the network, broadcast address, subnet mask, and host range.
4. Use the results. Apply them to network setup, server planning, or subnet design.

Example IP Subnet Calculation

Suppose your IP address is 192.168.10.77/26.

Step 1: Find the host bits.

Host bits = 32 − 26 = 6

Step 2: Find the total addresses.

Total IP addresses = 2^6 = 64

Step 3: Find the subnet mask.

The subnet mask is 255.255.255.192.

Step 4: Find the network range.

Block size = 256 − 192 = 64.

The last octet, 77, falls within the range 64–127.

Network address: 192.168.10.64

Broadcast address: 192.168.10.127

Step 5: Find the usable hosts.

First usable IP: 192.168.10.65

Last usable IP: 192.168.10.126

Usable hosts = 64 − 2 = 62.

So, this subnet has 64 total addresses and 62 usable host addresses.

Final Verdict

The IP Subnet Calculator makes IPv4 subnet planning much easier. It helps you find network details without doing each step by hand. Use it to check subnet masks, host ranges, and broadcast addresses. Always verify your subnet plan before applying it to a live network.

FAQs

What does an IP subnet calculator do?

It calculates network details from an IPv4 address and a CIDR prefix or subnet mask.

How do I find the subnet mask?

Use the CIDR prefix. For example, /24 gives the mask 255.255.255.0.

How many usable hosts does a /24 subnet have?

A typical /24 subnet has 256 total addresses and 254 usable host addresses.

What is the difference between a network address and a broadcast address?

The network address identifies the subnet. The broadcast address sends traffic to all hosts on that IPv4 subnet.

Can I calculate a /31 or /32 subnet?

Yes. A /31 can support two addresses on a point-to-point link. A /32 represents a single IP address.