Free Local utilities
IP/CIDR calculator
Calculate IPv4 or IPv6 network boundaries and address counts. IPv4 /31 uses point-to-point semantics; /32 is a single address. No network connections are made.
Bookmark
Use your browser’s bookmark command to save this page. It saves the tool link, not your inputs or results.
Only the tool link is copied. Inputs and results are never included.
Your inputs
Runs in your browser. Inputs and results are not uploaded or saved by this tool. Copy or download only what you intend to keep.
Text input: up to 256 KiB. Results are cleared when you leave the page.
How it works
Addresses are converted to integers to compute the network boundary and final address exactly, including IPv6 counts. IPv4 /31 and /32 counts follow their special host conventions.
Assumptions and limitations
No DNS lookup, routing test or network scan is performed. Calculated host counts do not prove which addresses are configured, reachable or usable in your network. IPv6 has no IPv4-style broadcast address.
How to use this tool
Enter an IPv4 or IPv6 address followed by / and its prefix length, then Calculate. Review the normalized network and address range. IPv4/IPv6 example buttons and the prefix slider edit the CIDR input. IPv4 masks and usable endpoints follow /31 and /32 special cases; IPv6 has no broadcast output. No address list is enumerated.
Worked example
Demonstration data only. Loading an example replaces the inputs but does not run the tool.
192.0.2.123/24 → 192.0.2.0/24 192.0.2.0 – 192.0.2.255
Frequently asked questions
What should I check before using this result?
No DNS lookup, routing test or network scan is performed. Calculated host counts do not prove which addresses are configured, reachable or usable in your network. IPv6 has no IPv4-style broadcast address.
Are my inputs or results saved automatically?
No. Processing stays in this browser and leaving the page clears the tool state. Copied or downloaded results remain under your control. Page-loading and privacy controls are described in the Privacy Policy.
Processing and privacy
No. Processing stays in this browser and leaving the page clears the tool state. Copied or downloaded results remain under your control. Page-loading and privacy controls are described in the Privacy Policy.
Privacy PolicyHelp
Enter an IPv4 or IPv6 address followed by / and its prefix length, then Calculate. Review the normalized network and address range. IPv4/IPv6 example buttons and the prefix slider edit the CIDR input. IPv4 masks and usable endpoints follow /31 and /32 special cases; IPv6 has no broadcast output. No address list is enumerated.
Runs in your browser. Inputs and results are not uploaded or saved by this tool. Copy or download only what you intend to keep.
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