Subnet Calculator
Calculate network address, broadcast address, and usable host range from an IP and CIDR prefix.
- Network Address
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- Broadcast Address
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- Subnet Mask
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- Wildcard Mask
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- First Usable Host
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- Last Usable Host
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- Total Addresses
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- Usable Hosts
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- IP Class
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Key features
Type an IPv4 address with a CIDR prefix, like 192.168.1.0/24, and every value updates instantly: network and broadcast address, subnet and wildcard mask, the first and last usable host, and how many usable addresses the subnet has.
This one doesn’t even have a network exception to mention — it’s plain arithmetic, computed entirely in your browser without contacting anything.
How to use
Enter an IP and CIDR prefix
Type an IPv4 address with a slash and prefix length, like 192.168.1.0/24.
Read the results
Every value — network, broadcast, mask, and usable host range — updates as soon as the input is valid.
Frequently asked questions
What does the CIDR prefix (the /24 part) mean?
It's the number of bits in the subnet mask that are fixed as the "network" portion — /24 means the first 24 bits are the network, leaving 8 bits (256 addresses) for hosts. A smaller number means a bigger subnet; a bigger number means a smaller one.
Why do /31 and /32 not follow the usual pattern?
A /32 identifies a single host, so there's no separate network or broadcast address. A /31 has exactly two addresses and, per RFC 3021, both are usable as point-to-point link endpoints instead of one being reserved as a broadcast address — the usual "usable = total minus 2" rule only applies to /30 and smaller prefixes.
Does the IP address I enter get sent anywhere?
No — this is pure arithmetic on the numbers you type, computed locally in your browser. There's no network request involved at all.