CIDR Subnet Calculator
Instantly calculate network, broadcast, and host range from an IP/CIDR
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🔒 Everything runs 100% in your browser. Your files and input are never uploaded to any server.
Enter an IPv4 address and a CIDR prefix (/0 to /32) to instantly get the network address, broadcast address, subnet mask, usable IP range, and host counts. It's handy for network engineers, sysadmins, and anyone configuring firewalls or splitting cloud VPC subnets, and since all math runs locally in your browser, no IP data is ever sent to a server.
How to use
- Enter the IPv4 address you want to calculate (e.g. 192.168.1.1)
- Enter a CIDR prefix between 0 and 32 (e.g. 24)
- The network address, broadcast address, and subnet mask appear automatically
- Check the usable IP range and host counts (usable vs. total)
FAQ
- How are /31 and /32 subnets handled?
- A /32 has exactly one usable host (itself). A /31 has no separate network/broadcast address, so both of its two IPs are treated as usable. Regular subnets (/0-/30) subtract the network and broadcast addresses from the usable host count.
- Does it support IPv6?
- No, only IPv4 addresses (e.g. 192.168.1.1) are supported. Entering an IPv6 address will show an invalid input message.
- Is my IP information sent anywhere?
- No. All calculations happen entirely in your browser — nothing is transmitted to or stored on a server.