IP Subnet Calculator — free online tool
Setting up a network and squinting at an IP address, trying to remember what a /24 actually means? Working out the broadcast address by hand is easy to get wrong, and one slip can take a whole afternoon to find. We added a free tool that does it for you — IP Subnet Calculator — right in your browser.
What it does
Type an IPv4 address with a /CIDR prefix (or a dotted subnet mask) and it gives you the network address, the broadcast address, the range of usable host addresses, the total host count and the wildcard mask. Everything you need to plan or check a subnet, on one screen.
Nothing leaves your device
The whole thing runs in your browser. The addresses you type are never uploaded and nothing is saved anywhere. You can use it on a work laptop or an offline machine and it works exactly the same.
How to use it
- Open IP Subnet Calculator.
- Enter an IPv4 address with a prefix like
/24, or a dotted mask. - Read off the network, broadcast, host range, host count and wildcard mask.
It's free with no limit. There are more small tools on the Apps page.