Subnet Calculator

Developer

Calculate the network address, broadcast, netmask and usable host count for any IPv4 subnet /0 to /32. Free and fully client-side; addresses never leave your browser.

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What is a Subnet Calculator?

A Subnet Calculator takes an IPv4 address and a prefix length and computes the network address, broadcast address, netmask, total number of hosts and usable hosts for that subnet. It is used when planning IP ranges, VLANs, subnets in cloud services and container networks.

A worked example

For 192.168.1.0/24 the network address is 192.168.1.0, the broadcast is 192.168.1.255, the netmask is 255.255.255.0, the total number of hosts is 256 and the usable hosts are 254.

Why are usable hosts fewer than total hosts?

The network address and the broadcast address are always reserved and cannot be assigned to a device. A /24 subnet therefore holds 256 addresses but offers 254 usable hosts.

Everything in one view

  • Network address and CIDR mask.
  • Broadcast address for the subnet.
  • Usable host range (network and broadcast excluded).
  • Total address count for the block.

Reading CIDR quickly

The /24 in 192.168.1.0/24 means the first 24 bits are fixed, leaving 8 host bits — 256 addresses, 254 usable. Each fewer / bit doubles the block: /23 doubles to 512, /25 halves to 128. The trend is the fastest mental shortcut.

How to use Subnet Calculator

Enter an IPv4 address and prefix to get the network, broadcast, netmask and host counts.

Use the controls above to provide your input or choose options, then review the result on the page.

Why use our Subnet Calculator

  • Calculates network, broadcast, netmask and host counts for an IPv4 subnet.
  • Complete the task with a focused Subnet Calculator workflow instead of switching between apps.
  • Open it in your browser and get started—no account or installation required.

Frequently Asked Questions

  • What is Subnet Calculator?

    Calculates network, broadcast, netmask and host counts for an IPv4 subnet.

  • How do I use Subnet Calculator?

    Type or paste your data into the field on this page and press the button. The result is calculated instantly in your browser — nothing is uploaded.

  • Is Subnet Calculator free?

    Yes, Subnet Calculator is completely free. No signup, no downloads and no usage limits.

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