IP Subnet Calculator
Calculate network addresses, broadcast addresses, subnet masks, usable host ranges, and address counts for IPv4 and IPv6 networks.
Run tool
The IP Subnet Calculator processes IPv4 and IPv6 network definitions provided in CIDR notation to determine subnet parameters, address allocations, and routing boundaries. When you enter an IP address with a prefix length, the tool calculates the canonical network address, broadcast address, netmask, and prefix length. It computes the total address capacity along with the usable host count, accounting for reserved network and broadcast boundaries when applicable. The utility displays the exact usable host range from the first assignable host to the last assignable host, reporting clear placeholders when no assignable host exists for very small prefixes. It also classifies the network based on standard IP address scopes, identifying private, global, and multicast designations. For IPv4 addresses, the calculator provides additional binary netmask details and subnet bit representations. If an address includes host bits rather than a strict network zero boundary, the parser normalizes the entry automatically to the correct subnet base.
Instructions
- Enter an IPv4 or IPv6 network address with its prefix length in CIDR notation, such as 192.168.1.0/24 or 10.0.0.0/8.
- Leave the input blank to use the default network value of 192.168.1.0/24.
- Click the calculate button to evaluate the network parameters.
- Review the resulting network address, broadcast address, netmask, usable host range, address counts, and classification.
Examples
- Calculate subnet parameters for 192.168.1.0/24 to view the network address (192.168.1.0), broadcast address (192.168.1.255), usable host range (192.168.1.1 to 192.168.1.254), and 254 usable hosts.
- Calculate subnet boundaries for 10.0.0.0/8 to inspect the total address pool of 16,777,216 addresses, netmask 255.0.0.0, and private network classification.
- Normalize a host address such as 172.16.5.42/16 to identify its canonical network boundary at 172.16.0.0/16.
FAQ
What happens if I enter an IP address containing host bits instead of zeros?
The calculator parses the address and automatically normalizes it to the correct base network boundary for the specified prefix.
How are usable host counts calculated?
The usable host count is calculated as the total address count minus two for standard subnets, with a minimum boundary of zero.
Does this calculator support IPv6 networks?
Yes, IPv6 addresses and prefix lengths are supported, returning total address counts, network addresses, and scope classifications.
What is shown when a subnet has no assignable host addresses?
When prefix sizes leave no distinct host addresses, the first and last usable host fields display an N/A designation.