Subnet Calculator - Free, Instant, In Your Browser
Enter an IPv4 address and CIDR prefix (like 24) to calculate the subnet's network address, broadcast address, and usable host range.
How to use Subnet Calculator
- 1Enter the required date(s) and details above.
- 2Click Calculate - Subnet Calculator runs instantly, right in your browser.
- 3Read your result below.
Your file is processed in your browser and is never uploaded.
Frequently Asked Questions
What's the formula?
The network address is the IP masked with the CIDR prefix; the broadcast address sets all host bits to 1; usable hosts exclude both of those, e.g. a /24 gives 254 usable hosts.
Is my data sent to a server?
No - everything runs entirely in your browser with JavaScript. Nothing is uploaded.