Loading…

How to use CIDR Calculator

Enter a CIDR like 192.168.1.10/24 and the tool computes the network and broadcast addresses, netmask, wildcard mask, first and last usable host, and host count.

Frequently asked questions

What does the /24 prefix mean?

It is the number of leading 1-bits in the netmask. /24 means the first 24 bits are the network and the last 8 bits address hosts.

Why is the host count total minus two?

The network and broadcast addresses are reserved, so a /24 has 256 addresses but only 254 usable hosts.

What happens with /31 and /32?

/32 is a single host and /31 is a two-address point-to-point link, so no separate usable-host range is reported.

More Developer Tools

HTTP Status Codes
Searchable HTTP code reference.
MIME Types
Extension — MIME lookup.
Diff Checker
Line-by-line visual differences.
Regex Tester Advanced
Flags, groups, replace, cheat sheet.
cURL Builder
Build cURL command from form.
cURL to Code
Convert cURL to JS/Python/PHP/Go.
JWT Debugger
Decode JWT segments and verify.
Chmod Calculator
Symbolic — octal permission grid.
Crontab Guru
Visual cron builder + readable output.
Semver Tools
Validate, compare and range-check semantic versions.
UUID Inspector
Detect UUID version, variant and embedded timestamp.
Basic Auth Generator
Build an HTTP Basic Authorization header from user/pass.

← View all Developer ToolsBrowse all 1,100+ tools →