This IP Address Calculator allows you to calculate detailed network information for both IPv4 and IPv6 addresses, including subnet masks, network prefixes, usable address ranges, and CIDR or prefix notation. It is built for network administrators, IT professionals, students, and engineers who need fast and accurate IP calculations without manually converting binary or hexadecimal values.

What this tool can do:

  • Calculate IPv4 subnet masks and CIDR notation
  • Determine network and broadcast addresses (IPv4)
  • Show usable host ranges for IPv4 subnets
  • Interpret IPv6 prefix lengths
  • Validate IPv4 and IPv6 address formats

Advanced IP Subnet Calculator

Supports IPv4 CIDR, IPv4 with subnet mask, and IPv6 CIDR. Example: 10.0.0.1/16, 10.0.0.1 255.255.0.0, 2001:db8::/48

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How IP Addressing Works

What Is Subnetting?

Subnetting is the process of dividing an IP network into smaller, logical networks called subnets. This allows better control of traffic, improved security, and more efficient use of IP address space. Routers operate at the boundary between subnets and control how traffic is forwarded between them. Each subnet shares a common network prefix, while individual devices are identified by a unique host portion of the address.

IPv4 and IPv6 Address Structure

An IP address is made up of two parts:

  • Network prefix – identifies the network
  • Host identifier – identifies a device within that network

The size of the network prefix determines how many subnets and hosts are available.

IPv4 Addressing

IPv4 uses 32-bit addresses, typically written in dotted-decimal format (for example, 192.168.1.1).
Subnet size is defined using either:

  • CIDR notation (such as /24)
  • Subnet masks (such as 255.255.255.0)

All devices within the same IPv4 subnet share the same network prefix. The first and last addresses in each subnet are reserved for the network and broadcast addresses.

IPv6 Addressing

IPv6 uses 128-bit addresses, written in hexadecimal and separated by colons. Instead of subnet masks, IPv6 relies entirely on prefix lengths. A /64 prefix is standard for most IPv6 networks and provides a fixed subnet size. IPv6 does not use broadcast addresses and was designed to simplify subnetting while supporting a much larger address space.

How This Calculator Helps

This IP calculator automatically interprets:

  • IPv4 subnet masks and CIDR notation
  • IPv6 prefix lengths
  • Network boundaries and usable address ranges