Ip Subnet Calculator

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Advanced IP Subnet Calculator

/32 (255.255.255.255) /31 (255.255.255.254) /30 (255.255.255.252) /29 (255.255.255.248) /28 (255.255.255.240) /27 (255.255.255.224) /26 (255.255.255.192) /25 (255.255.255.128) /24 (255.255.255.0) /23 (255.255.254.0) /22 (255.255.252.0) /21 (255.255.248.0) /20 (255.255.240.0) /19 (255.255.224.0) /18 (255.255.192.0) /17 (255.255.128.0) /16 (255.255.0.0) /15 (254.0.0.0) /14 (252.0.0.0) /13 (248.0.0.0) /12 (240.0.0.0) /11 (224.0.0.0) /10 (192.0.0.0) /9 (128.0.0.0) /8 (255.0.0.0)
Network Address:
Broadcast Address:
Usable Host Range:
Total Number of Hosts:
Usable Number of Hosts:
Subnet Mask:
Wildcard Mask:
CIDR Notation:

Understanding IP Subnetting

Subnetting is the process of dividing a single physical network into several logical sub-networks (subnets). This process allows network administrators to organize IP addresses more efficiently, reduce network traffic by minimizing broadcast domains, and enhance security by isolating sections of the network.

An IP address consists of two main parts: the Network ID and the Host ID. The subnet mask determines where the network part ends and the host part begins. By using an IP Subnet Calculator, you can instantly find the boundaries of your network and ensure your routing is configured correctly.

Key Subnetting Terms

  • Network Address: The first address in a subnet, used to identify the network itself. It cannot be assigned to a host.
  • Broadcast Address: The last address in a subnet, used to send data to all hosts on that subnet simultaneously.
  • Usable IP Range: The specific set of IP addresses between the network and broadcast addresses that can be assigned to devices like computers, printers, and routers.
  • CIDR (Classless Inter-Domain Routing): A modern method of IP addressing that uses a slash followed by a number (e.g., /24) to represent the length of the subnet mask prefix.
Example Breakdown: 192.168.1.0/24
• Subnet Mask: 255.255.255.0
• Network ID: 192.168.1.0
• Usable Range: 192.168.1.1 to 192.168.1.254
• Broadcast: 192.168.1.255
• Total Hosts: 256 (254 Usable)

Why Use an IP Subnet Calculator?

Calculating subnets manually involves binary math and bitwise operations, which are prone to human error. This tool is essential for network engineers, IT students, and systems administrators to quickly verify network designs, troubleshoot connectivity issues, and plan for future network expansion without needing to manually convert octets to 32-bit binary strings.

function calculateSubnet() { var ipStr = document.getElementById('ipAddress').value.trim(); var cidr = parseInt(document.getElementById('cidrPrefix').value); // Validate IP format var ipPattern = /^(\d{1,3}\.){3}\d{1,3}$/; if (!ipPattern.test(ipStr)) { alert("Please enter a valid IP address (e.g., 192.168.1.1)"); return; } var octets = ipStr.split('.'); var ipNum = 0; for (var i = 0; i < 4; i++) { var part = parseInt(octets[i]); if (part 255) { alert("IP octets must be between 0 and 255."); return; } ipNum = (ipNum <>> 0; // Calculate Mask var mask = 0; if (cidr > 0) { mask = (0xFFFFFFFF <>> 0; } // Calculate values var networkNum = (ipNum & mask) >>> 0; var wildcardNum = (~mask) >>> 0; var broadcastNum = (networkNum | wildcardNum) >>> 0; var totalHosts = Math.pow(2, (32 – cidr)); var usableHosts = totalHosts > 2 ? totalHosts – 2 : 0; // /31 and /32 are special cases if (cidr === 31) usableHosts = 2; if (cidr === 32) usableHosts = 1; // Convert back to dot notation function numToDot(num) { return ((num >>> 24) & 0xFF) + "." + ((num >>> 16) & 0xFF) + "." + ((num >>> 8) & 0xFF) + "." + (num & 0xFF); } var firstUsableNum = networkNum + 1; var lastUsableNum = broadcastNum – 1; // Handle range display for small subnets var rangeStr = ""; if (cidr === 32) { rangeStr = numToDot(networkNum); } else if (cidr === 31) { rangeStr = numToDot(networkNum) + " – " + numToDot(broadcastNum); } else { rangeStr = numToDot(firstUsableNum) + " – " + numToDot(lastUsableNum); } // Update UI document.getElementById('resNetwork').innerText = numToDot(networkNum); document.getElementById('resBroadcast').innerText = numToDot(broadcastNum); document.getElementById('resRange').innerText = rangeStr; document.getElementById('resTotalHosts').innerText = totalHosts.toLocaleString(); document.getElementById('resUsableHosts').innerText = usableHosts.toLocaleString(); document.getElementById('resMask').innerText = numToDot(mask); document.getElementById('resWildcard').innerText = numToDot(wildcardNum); document.getElementById('resCIDR').innerText = "/" + cidr; document.getElementById('results-area').style.display = 'block'; }

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