Runs locally
Subnet Calculator
Network, mask, hosts and broadcast from CIDR.
Ctrl+Enter runs. Ctrl+Shift+Backspace clears.
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IPv4 CIDR math only. It does not scan or contact any address.
About this tool
Plan a network, a VPC or firewall rules. Enter an IPv4 address with a prefix length and see the network address, subnet mask, usable host range, broadcast address and number of hosts.
How to use it
- 01
Enter the CIDR, for example 10.0.0.0/16.
- 02
Read the network, mask and broadcast.
- 03
Check the first and last usable host and the host count.
FAQ
Frequently asked questions
Does it support IPv6?
No. The calculator does IPv4 CIDR math only.
Does it scan the network?
No. It only calculates; no address is scanned or contacted.