IP Range to CIDR Blocks
Convert an arbitrary start–end IPv4 range into the minimal list of CIDR blocks that exactly covers it — for firewall rules, route tables and allowlists.
About IP Range to CIDR Blocks
Convert an arbitrary start–end IPv4 range into the minimal list of CIDR blocks that exactly covers it — for firewall rules, route tables and allowlists. IP Range to CIDR Blocks runs entirely in your browser — your input never leaves your device and there is nothing to install. Just paste your text and copy the result the moment it appears.
How to use IP Range to CIDR Blocks
- 1Paste or type your input into the box above — a sample is pre-filled so you can try it instantly.
- 2Set any options on offer (mode, key, format) to match what you need.
- 3The result appears the moment you type — no button to press, no waiting.
- 4Click Copy to grab the output — IP Range to CIDR Blocks keeps everything on your device.
Why use IP Range to CIDR Blocks?
- ✓Handles edge cases and formatting correctly so you get the right answer the first time
- ✓Processes everything locally in the browser — fast and responsive even on large inputs
- ✓100% free with no sign-up, no watermark and no usage limits
- ✓Runs entirely in your browser — your text and keys are never uploaded, stored or logged
- ✓Works offline once loaded, with instant results and one-click copy
Frequently asked questions
What does IP Range to CIDR Blocks do?+
Convert an arbitrary start–end IPv4 range into the minimal list of CIDR blocks that exactly covers it — for firewall rules, route tables and allowlists. It all happens client-side in your browser, which keeps it fast and completely private.
Do I need to install anything or sign up?+
No — IP Range to CIDR Blocks works instantly in any modern browser with no account, no download and no usage limits.
Is it free to use?+
Yes — completely free with no sign-up, no account and no usage limits. There is no paywall, so you can encode, decode and convert as much as you like.
Is my data private and secure?+
Yes. This tool runs entirely in your browser using client-side JavaScript — your input is never uploaded to a server, stored or logged. Once the page has loaded you can use it offline, which makes it safe for tokens, keys and confidential data.
Related Developer tools
JSON to TypeScript Interface Generator
Paste JSON and get clean TypeScript interfaces instantly — nested objects become named interfaces, arrays of objects are merged with optional properties detected, unions inferred. 100% client-side.
● LiveIPv4 Subnet Calculator
Enter an IP and CIDR prefix to get the network, broadcast, mask, wildcard, host range and usable host count — the complete subnet breakdown, instantly.
● LiveCIDR to Subnet Mask Converter
Convert a CIDR prefix (/0–/32) to its dotted-decimal subnet mask and wildcard mask, and back again — with host counts for each prefix length.
● Live