IP in Subnet — Contains / Overlap
Check whether an IP is inside a CIDR, or whether two CIDRs overlap.
Developer notes
Same family required. Forced family → error on mismatch. 64 KiB limit.
Options
- Mode
- contains = IP ∈ CIDR; overlap = intersection of two CIDRs.
- Family
- auto, or force ipv4 / ipv6 (mismatch → error).
When teams pick this route
Smoke-test an ACL rule. Check whether two prefixes intersect.
Worked examples
Contains
Before
After
Overlap
Before
After
Related networking tools
For subnet calculations, use subnet-calculator. Back to the networking tools hub.
IP in subnet FAQ
Contains & overlap
When should I use the number-base converter instead?
To convert an integer between bases 2–36 (hex of a number, binary of a value), use number-base-converter. Networking tools compute subnets and CIDRs, not general base conversion.
Are IP addresses uploaded?
No. All math runs locally in your browser. Nothing is uploaded to FastMinify.
What is the size limit?
64 KiB (UTF-8) for the combined input fields of each tool.
Networking / IP
CIDR, subnets, and IPv4/IPv6 helpers — in your browser.
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