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🔁 IP Range to CIDR
Cloud security groups and firewall rules often accept CIDR but not arbitrary ranges. This tool takes a start and end IPv4, and returns the minimum CIDR blocks that exactly cover everything in between — no more, no less.
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Examples
Even range
Input
10.0.0.0 - 10.0.0.255Output
10.0.0.0/24Odd boundaries
Input
10.0.0.5 - 10.0.0.20Output
10.0.0.5/32, 10.0.0.6/31, 10.0.0.8/29, 10.0.0.16/30, 10.0.0.20/32Frequently asked questions
Why so many blocks for an odd range?
CIDR blocks must align on power-of-2 boundaries. An uneven range needs multiple aligned blocks to cover it exactly.
About this calculator
IP Range to CIDR runs entirely in your browser using standard formulas. No data is sent to any server. We don't share your inputs with lenders, brokers, or anyone else — there's no funnel and no follow-up email.
Related tools
- 🧮 Subnet / CIDR Calculator — Calculate network, broadcast, host range, mask from any CIDR notation.
- 🎯 CIDR Contains Check — Check if an IP address is inside a CIDR block.
- 🧩 CIDR Aggregator — Merge a list of CIDR blocks into the smallest equivalent set.
Why this tool
vs typical free network-tools sites
| NetToolset | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for advanced features) |
| Ads inside the tool | No | Yes (banner + interstitial) |
| Logs your IP / queries | No | Yes (often resold) |
| Data sent to a server | Math runs in browser; lookups hit Cloudflare DoH directly | Yes (all goes through their server) |
| Open source | Yes | No |
| Bookmarkable URL per tool | Yes | Mixed |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |