CIDR Notation Converter
Bulk-convert between CIDR blocks, IP ranges, netmasks, and wildcard masks with range aggregation. Free, fast, and works entirely in your browser with no sign-up required.
CIDR Notation Converter
Bulk-convert between CIDR blocks, IP ranges, netmasks, and wildcard masks. Includes range aggregation into minimum CIDR blocks.
Bulk CIDR → IP Range
About CIDR Notation
CIDR (Classless Inter-Domain Routing) expresses an IP network as a base address plus a prefix length, e.g. 192.168.1.0/24. This tool handles four common bulk conversions for IPv4.
The Range → CIDR tab uses a greedy aggregation algorithm to produce the minimum set of CIDR blocks that exactly cover an arbitrary IP range — useful for firewall rules, ACLs, and routing tables.
Frequently Asked Questions
What does it do?
Four IPv4 conversions in bulk: CIDR to IP range, IP range to minimum CIDR blocks, netmask to/from CIDR, and wildcard to CIDR. Paste one entry per line, export CSV.
How does range-to-CIDR work?
Greedy algorithm: at each step find the largest CIDR aligned to the start and fitting the remaining range. Produces the minimum set of CIDRs exactly covering the range — useful for firewall rules and ACLs.
How is it different from Subnet Calculator?
Subnet Calculator analyzes a single subnet in depth. CIDR Converter is optimized for bulk conversion and range-to-CIDR aggregation, accepting many entries at once.
Is the CIDR Notation Converter free to use?
Yes, the CIDR Notation Converter is 100% free with no registration, no hidden fees, and no usage limits. All processing happens locally in your browser, ensuring complete privacy.
Is my data safe with this tool?
Absolutely. The CIDR Notation Converter processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.
Does the CIDR Notation Converter work on mobile devices?
Yes, the CIDR Notation Converter is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.
Do I need to create an account to use this tool?
No account or registration is needed. Simply open the CIDR Notation Converter in your browser and start using it immediately. There are no sign-up walls or usage restrictions.
How do I use the CIDR Notation Converter?
Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.
Which browsers are supported?
The CIDR Notation Converter works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.
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About CIDR Notation Converter
CIDR Notation Converter is a free, browser-based tool in our Utility Tools collection. Everything runs locally on your device — no uploads, no sign-up, and your data stays private.