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IP Subnet Calculator

Calculate IPv4 and IPv6 subnets, masks and host ranges.


IP Subnet Calculator

The IP Subnet Mask Calculator enables subnet network calculations for both IPv4 and IPv6 addresses, including network class information, subnet details, and binary representations.

How to calculate an IP subnet

A subnet is a block of IP addresses defined by a network address and a prefix length, written in CIDR notation such as 192.168.1.0/24. This calculator shows the network address, broadcast address, usable host range, subnet mask and number of addresses for any IPv4 or IPv6 block.

How to use it

  1. Enter an IP address with its prefix, for example 10.0.0.0/22.
  2. Run the calculation.
  3. Read the network, mask, first and last usable host, and total hosts.

Example

192.168.1.0/24 has the subnet mask 255.255.255.0 and 256 addresses, of which 254 are usable (192.168.1.1 to 192.168.1.254). The first address identifies the network and the last one, 192.168.1.255, is the broadcast address.

Good to know

  • Each step down in prefix length doubles the number of addresses: /24 = 256, /23 = 512, /22 = 1,024.
  • For IPv4, subtract 2 from the total to get the usable hosts. /31 and /32 are special cases.
  • IPv6 subnets are far larger. A standard LAN uses /64, which contains about 18 quintillion addresses.

Frequently asked questions

What does /24 mean?

The first 24 bits of the address identify the network and the remaining 8 bits identify hosts inside it.

Which subnet should I use for a small office?

A /24 with 254 hosts is the usual choice. Smaller subnets such as /27 (30 hosts) are handy for separating cameras or guest devices.

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