CIDR Validator
Paste a CIDR notation to check whether it is valid — complete with the reason if it is invalid and a component breakdown if it is valid. Everything is processed on your device.
Everything runs in your browser. Your data is never sent to our servers.
Example
Example Input
192.168.0.0/24
Example Output
✓ VALID — 256 addresses, 254 hosts
How to Use
- 1Paste the a CIDR notation you want to check into the input box.
- 2If the tool offers extra options (e.g. dialect, flags, or variant), set them as needed.
- 3Click Validate (or press Ctrl+Enter).
- 4Read the result badge — VALID, INVALID, or VALID with a warning — along with the details and the list of issues, if any.
About CIDR Validator
CIDR Validator checks a CIDR notation (e.g. 192.168.0.0/24 or 2001:db8::/32): the address part must be a valid IPv4/IPv6 and the prefix length must be in the correct range (0–32 for IPv4, 0–128 for IPv6). For IPv4, it also computes the total and usable host counts.
Useful when setting up subnets, firewall rules, or routes. For full subnet math, see the CIDR calculator in the Calculator category.
FAQ
Is my data sent to a server?
No. All validation runs in your browser with JavaScript. Nothing is uploaded, logged, or stored on our servers — safe for sensitive data.
How is this validator different from a parser or formatter?
A validator answers one question: is this input correct/valid? It returns a valid/invalid badge with the reason. A parser breaks input into its components, and a formatter tidies its layout. Use a validator when you just need to confirm something is sound before using it.