IP in Subnet Checker
Check whether an IPv4 address belongs to a CIDR subnet. Shows the network address, broadcast address and usable host range.
Last reviewed by the Radiatus Cloud team
Check whether an IPv4 address falls inside a given CIDR subnet.
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Check if an IP is inside a subnet
This tool tells you whether a particular IPv4 address belongs to a CIDR subnet. It works by applying the subnet mask to both the address you are testing and the network address: if the masked results match, the address lies inside the subnet. Alongside the yes-or-no answer it reports the network address, the broadcast address and the range of usable host addresses, giving you the full picture of the block.
Enter the address and the subnet in standard CIDR notation, such as 192.168.1.0/24, and the check is instant.
When subnet membership matters
Network administrators constantly need to know whether an address falls within a given range, whether writing firewall and access rules, troubleshooting routing, or planning address assignments. A device can only communicate directly with others in the same subnet, so membership determines whether traffic is local or must pass through a router.
The calculation uses the same bitwise logic that routers and operating systems use internally, so the answer matches how real equipment behaves. All processing happens locally in your browser, and no lookups are sent anywhere.
Related tools
- Port Scanner — Check which common ports respond on a host and understand what each exposed service means. Scan only systems you are authorised to test.
- DNS Misconfiguration — Analyze DNS records (TXT, SPF) for security gaps.
- TLS Compat Tester — Check client-server compatibility for TLS versions.
- Firewall Rule Risk — Evaluate firewall rules for over-permissive exposure.
Frequently Asked Questions
How does the checker decide membership?
It applies the subnet mask to both the test address and the network. If the masked values are equal, the address is inside the subnet.
Does the check include the network and broadcast addresses?
Yes. Membership covers every address in the block, including the network and broadcast addresses. The usable host range excludes those two.
What CIDR sizes are supported?
Any IPv4 prefix from /0 to /32. For /31 and /32 there are no separate network and broadcast addresses, and the tool adjusts the host range accordingly.
Why does membership matter?
Devices in the same subnet communicate directly, while traffic to other subnets must go through a router, so membership affects routing and firewall decisions.
Is any network request made?
No. The check is pure arithmetic performed in your browser, so nothing about the address is sent to a server.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Enter an IP address and a CIDR subnet to test membership.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
Related Tools
Port Scanner
NetworkCheck which common ports respond on a host and understand what each exposed service means. Scan only systems you are authorised to test.
DNS Misconfiguration
NetworkAnalyze DNS records (TXT, SPF) for security gaps.
TLS Compat Tester
NetworkCheck client-server compatibility for TLS versions.