IP Subnet Calculator
Turn an IPv4 address and CIDR prefix into its network, broadcast, and usable range.
Quick answer: enter your details below and click Calculate Subnet — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
I
Converters & Utilities
Enter your details below.
How to use
- Enter an IPv4 address followed by a slash and a prefix, such as /24.
- Check the prefix matches the network you mean.
- Click Calculate Subnet.
- Read off the network, broadcast, and usable host range.
About this tool
A CIDR address packs a host address and a network size into one short string, and this calculator unpacks it. From an address such as 192.168.1.10/24 it derives the network address, the broadcast address, the first and last usable hosts, and the count of usable hosts. The maths runs entirely in your browser, so no address you check is sent anywhere.
Frequently asked questions
Why does a /24 network have 254 usable hosts?
A /24 leaves 8 host bits, giving 256 addresses, minus the network address itself and the broadcast address.
What about /31 and /32?
Those prefixes leave no ordinary usable range, so the calculator reports zero usable hosts for them.