CIDR Overlap & Contains Checker
Check if two IPv4 CIDR subnets overlap and whether a host IP falls inside either network block.
About this tool
Compare two IPv4 CIDR blocks for overlap — essential for VPC peering, firewall rules, and route planning before you deploy. Also test whether a specific host IP belongs to network A, network B, or neither.
What you get
- Overlap yes/no verdict with plain-language message
- Whether an optional IP is inside CIDR A and/or CIDR B
- Network A bounds: network address and broadcast
- Network B bounds: network address and broadcast
- Normalized CIDR notation for each input
- Parse errors for invalid CIDR or IP format
How to use
Enter two CIDRs to test overlap, optionally add a host IP for membership. Results update live as you type.
Related searches
- cidr overlap
- subnet overlap checker
FAQ
How to check if two subnets overlap?
Enter two IPv4 CIDR blocks and read whether their address ranges intersect, plus the shared range when they do.
How to test if an IP is in a CIDR range?
Provide one CIDR and a host IP to see membership yes/no with normalized network bounds.
Why do overlapping subnets cause routing problems?
Overlapping ranges make it ambiguous which path should carry traffic, breaking VPC peering, firewall rules, and static routes.
How to find the shared range of two CIDR blocks?
When overlap is detected, the tool reports the intersecting address span so you can redesign allocations.
How to plan non-overlapping VPC CIDR blocks before peering?
Enter each proposed VPC range pairwise—the overlap check flags conflicts and shows the intersecting span before you commit allocations.
By using this tool you agree to our Terms of Use and Privacy Policy. Results are provided as-is without warranty.