Also available in the Chrome extension Every Zase tool also lives in the free Developer Toolkit by Zase extension: fully offline, in a window or the side panel, one keyboard shortcut away.
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About this IP Subnet Calculator
The IP Subnet Calculator works out an IPv4 subnet from an address and CIDR prefix: network and broadcast addresses, the wildcard and subnet masks, and the first, last and total usable host range. The maths you need when planning networks, firewall rules or cloud VPC ranges.
How to use the IP Subnet Calculator
- Enter an IPv4 address and a CIDR prefix, such as 192.168.1.0 and 24.
- Read the network, broadcast, mask and host range results.
- Adjust the prefix to see how the range grows or shrinks.
Good to know
- Each step down in prefix size doubles the address count; each step up halves it.
- A /32 is a single host, which is why firewall rules use it for one machine.
- Cloud VPC ranges cannot overlap; working the ranges out here first prevents painful rebuilds.