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🌐 Subnet Calculator

Calculate IPv4 CIDR ranges, netmask, wildcard mask, broadcast address, usable hosts, and copyable subnet reports.

Subnet checks

Validates dotted IPv4 input and CIDR prefixes from /0 to /32. Warns on very broad ranges and /31 or /32 point-to-point/host-route semantics.

Runs in your browser

Subnet math runs locally in your browser. This does not scan or contact any network.

What this tool does

Subnet Calculator computes CIDR ranges, masks, usable addresses, broadcast addresses, and network boundaries.

Why it is useful

It helps network engineers and developers plan IP ranges, firewall rules, VPCs, VPNs, and documentation.

How it works

The browser applies IPv4 subnet math from the address and prefix length.

Best input

Enter the network address or host address with the intended CIDR prefix.

Network tip

Confirm cloud-provider reserved addresses and routing rules before allocating subnets.

Privacy note

Subnet math runs locally in your browser.

Important limitation

Usable-address counts and reserved addresses can vary by provider, protocol, and network design.

Quick answers

What does /24 mean?

It means 24 network bits, commonly 256 IPv4 addresses before reservations.

Does this scan my network?

No. It only calculates address ranges.

API examples

Call the same deterministic core through Utilito’s compact API router. Send only data you intentionally submit to the server-side endpoint.

Try in API playground →Schema →
Calculate a subnet with curl
curl
curl -X POST https://utilito.dev/api/run \
  -H "Content-Type: application/json" \
  -d '{"tool_id":"subnet-calculator","input":{"ip":"192.168.1.42","cidr":24}}'
Calculate a subnet from JavaScript
javascript
const res = await fetch('https://utilito.dev/api/run', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    tool_id: 'subnet-calculator',
    input: { ip: '192.168.1.42', cidr: 24 }
  })
});
const data = await res.json();
console.log(data.result.output || data.result.report);
Calculate a subnet from Python
python
import requests
payload = {
    "tool_id": "subnet-calculator",
    "input": {"ip": "192.168.1.42", "cidr": 24},
}
result = requests.post("https://utilito.dev/api/run", json=payload).json()["result"]
print(result.get("output") or result.get("report"))

Common Use Cases

Plan a VPC subnet

Check network, broadcast, and usable host ranges before allocating cloud subnets.

Document firewall ranges

Convert a host IP and prefix into an explicit network CIDR and address range.

Network troubleshooting workflow

Pair subnet planning with DNS, headers, redirects, status codes, SSL checks, and webhook debugging.

🌍DNS Lookup🌐HTTP Status Codes📡HTTP Header Checker↪️URL Redirect Checker🔒SSL Certificate Checker🪝Webhook Tester
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