Subnet Calculator
Compute network, broadcast, mask, host range and counts for an IPv4/IPv6 CIDR.
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Enter a network (cidr) above and press Run to start the check.
About the Subnet Calculator
The Subnet Calculator takes an IPv4 or IPv6 address in CIDR notation and computes everything you need to plan a network: the network address, broadcast address, subnet mask, wildcard mask, usable host range, and total host count. It works for any prefix length, making it handy for VLSM design, firewall rules, and DHCP scope planning. Results update as soon as you change the address or prefix.
How to use
- Enter an address in CIDR notation, such as 192.168.1.0/24.
- Submit to calculate the network and broadcast addresses.
- Read the subnet mask, wildcard mask, and usable host range.
- Adjust the prefix length to compare different subnet sizes.
Frequently asked questions
- What is a wildcard mask?
- A wildcard mask is the bitwise inverse of the subnet mask. Devices like Cisco ACLs use it to match ranges of addresses.
- Why is the usable host count two less than the total?
- In IPv4 the network address and the broadcast address are reserved, so they cannot be assigned to hosts. A /24, for example, has 256 addresses but 254 usable.
- Does this support IPv6?
- Yes. Enter an IPv6 prefix such as 2001:db8::/48 and the calculator returns the network range and address count for that block.