What does the IP subnet calculator return?

For an IPv4 CIDR block it returns the network address, netmask, wildcard mask, broadcast address, the first and last host, and the count of usable hosts. For example, 192.168.1.10/24 gives network 192.168.1.0, broadcast 192.168.1.255 and 254 usable hosts.

How do I write the address in CIDR form?

Put the IPv4 address, a slash, and the prefix length together with no spaces, like 10.0.0.5/16 or 192.168.1.10/24. The prefix can be any value from 0 to 32 and decides how many bits belong to the network.

Why are there fewer usable hosts than total addresses?

Each block reserves two addresses: the network address itself and the broadcast address. So a /24 holds 256 addresses but only 254 are usable for actual hosts.

Is my IP address sent to a server?

No. The whole calculation runs in your browser using plain bit math, so the address you type never leaves your device and nothing is uploaded or logged.

IP Subnet Calculator

Input

Output

What the IP Subnet Calculator does

The IP Subnet Calculator takes a single IPv4 address written in CIDR notation and works out every value you need to plan or document a network. From one entry like 192.168.1.10/24 it derives the network address, the netmask, the wildcard mask, the broadcast address, the first and last usable host, and the total count of usable hosts.

It helps network engineers, sysadmins, students and anyone configuring routers, firewalls or cloud VPCs. Instead of doing binary math by hand, you get the full picture of a subnet in one step.

How to use it

Type an IPv4 address in CIDR form into the input box, for example 192.168.1.10/24.
Press the Calculate button.
Read the results, including network, netmask, wildcard, broadcast and the usable host range.
Use Copy to grab the output for your notes, tickets or config files.

A worked example

Enter 192.168.1.10/24. The network address comes out as 192.168.1.0 and the broadcast address as 192.168.1.255. The netmask is 255.255.255.0, the usable range runs from 192.168.1.1 to 192.168.1.254, and that gives 254 usable hosts. Shrinking the prefix to /25 would split the same space into two smaller blocks of 126 hosts each.

Everything runs right in your browser, so it is private, fast and free with no upload and no sign-up.

Frequently asked questions

What does the IP subnet calculator return?: For an IPv4 CIDR block it returns the network address, netmask, wildcard mask, broadcast address, the first and last host, and the count of usable hosts. For example, 192.168.1.10/24 gives network 192.168.1.0, broadcast 192.168.1.255 and 254 usable hosts.
How do I write the address in CIDR form?: Put the IPv4 address, a slash, and the prefix length together with no spaces, like 10.0.0.5/16 or 192.168.1.10/24. The prefix can be any value from 0 to 32 and decides how many bits belong to the network.
Why are there fewer usable hosts than total addresses?: Each block reserves two addresses: the network address itself and the broadcast address. So a /24 holds 256 addresses but only 254 are usable for actual hosts.
Is my IP address sent to a server?: No. The whole calculation runs in your browser using plain bit math, so the address you type never leaves your device and nothing is uploaded or logged.

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Last updated: June 17, 2026