Subnet Calculator
Calculate subnet mask and host range from IPv4/IPv6 CIDR
IPv4/IPv6 Subnet Calculator Online
Calculate all subnet information from CIDR notation with our free calculator. Enter an IPv4 address like 192.168.1.0/24 or IPv6 like 2001:db8::/48 to instantly get: network address, broadcast address, subnet mask, wildcard mask, host range and number of available hosts. Essential tool for network administrators, engineers and students.
How It Works
- Enter the IP address with CIDR prefix (e.g. 192.168.0.0/24)
- IPv4 or IPv6 type is detected automatically
- Results are calculated and displayed instantly
- Click the copy icon next to each value to copy it to clipboard
- Use the quick examples to test the calculator
Frequently Asked Questions
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) is a method for specifying IP addresses and subnets. The number after the slash (e.g. /24) indicates the number of bits used for the network portion. /24 corresponds to subnet mask 255.255.255.0 with 254 usable hosts.
What are network and broadcast addresses?
The Network Address is the first address of the subnet (e.g. 192.168.1.0) and identifies the network. The Broadcast Address is the last (e.g. 192.168.1.255) and is used to send messages to all hosts in the subnet. Neither can be assigned to a host.
What is a wildcard mask?
The Wildcard Mask (or Inverse Mask) is the complement of the subnet mask. It is mainly used in Cisco ACLs (Access Control Lists) and the OSPF protocol to specify which bits of the address must match.