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Subnet / CIDR Calculator
Calculate IPv4 subnet details directly in your browser. Paste a host address like
192.168.10.42, or paste full CIDR notation like 192.168.10.42/24,
and this tool will show the network base, broadcast address, subnet mask, wildcard mask,
usable host range, and host counts without uploading anything.
/24
CIDR block
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Subnet mask
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Wildcard mask
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Usable hosts
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Address space
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This is a quick block you can paste into notes, tickets, or config comments.
Useful when you want to see where the network bits stop and the host bits begin.
What this tool does
It calculates the IPv4 network base, broadcast address, masks, host range, and host counts for the subnet you enter.
Why it is private
The IP math happens entirely in your browser, so the addresses you test here never leave the page and never touch server memory.
What the numbers mean
- Subnet mask: the dotted-decimal version of the prefix length.
- Wildcard mask: the inverse mask often used in ACLs and older network configs.
- Usable hosts: the addresses typically available to hosts after reserving the network and broadcast addresses.
Helpful note
/31 and /32 are handled specially: /31 is treated as a two-address point-to-point block, and /32 is treated as a single host route.