Ip Subnet Calculator

IP Subnet Calculator

Use this calculator to determine the network address, broadcast address, host range, and number of usable hosts for a given IP address and subnet mask.

.subnet-calculator-container { font-family: Arial, sans-serif; max-width: 600px; margin: 20px auto; padding: 20px; border: 1px solid #ccc; border-radius: 8px; background-color: #f9f9f9; } .subnet-calculator-container h2 { text-align: center; color: #333; margin-bottom: 20px; } .subnet-calculator-container p { margin-bottom: 15px; line-height: 1.6; } .calculator-input-group { margin-bottom: 15px; } .calculator-input-group label { display: block; margin-bottom: 5px; font-weight: bold; color: #555; } .calculator-input-group input[type="text"] { width: calc(100% – 22px); padding: 10px; border: 1px solid #ddd; border-radius: 4px; font-size: 16px; } .subnet-calculator-container button { display: block; width: 100%; padding: 12px 20px; background-color: #007bff; color: white; border: none; border-radius: 4px; font-size: 18px; cursor: pointer; transition: background-color 0.3s ease; margin-top: 20px; } .subnet-calculator-container button:hover { background-color: #0056b3; } .calculator-result { margin-top: 25px; padding: 15px; border: 1px solid #e0e0e0; border-radius: 4px; background-color: #e9ecef; min-height: 50px; } .calculator-result p { margin: 8px 0; font-size: 16px; color: #333; } .calculator-result strong { color: #000; } .error-message { color: red; font-weight: bold; } function calculateSubnet() { var ipAddressInput = document.getElementById("ipAddress").value.trim(); var subnetMaskInput = document.getElementById("subnetMask").value.trim(); var resultDiv = document.getElementById("subnetResult"); resultDiv.innerHTML = ""; function isValidIp(ip) { var parts = ip.split('.'); if (parts.length !== 4) return false; for (var i = 0; i < 4; i++) { var part = parseInt(parts[i], 10); if (isNaN(part) || part 255) return false; } return true; } function ipToBinary(ip) { return ip.split('.').map(function(octet) { return ('00000000' + parseInt(octet, 10).toString(2)).slice(-8); }).join("); } function binaryToIp(binary) { var ip = []; for (var i = 0; i < 32; i += 8) { ip.push(parseInt(binary.substring(i, i + 8), 2)); } return ip.join('.'); } function cidrToDottedDecimal(cidr) { var numBits = parseInt(cidr.substring(1), 10); if (isNaN(numBits) || numBits 32) return null; var maskBinary = "; for (var i = 0; i < 32; i++) { maskBinary += (i < numBits) ? '1' : '0'; } return binaryToIp(maskBinary); } function dottedDecimalToCidr(mask) { if (!isValidIp(mask)) return null; var maskBinary = ipToBinary(mask); var numBits = 0; for (var i = 0; i < maskBinary.length; i++) { if (maskBinary[i] === '1') { numBits++; } else { for (var j = i; j < maskBinary.length; j++) { if (maskBinary[j] === '1') return null; } break; } } return '/' + numBits; } if (!isValidIp(ipAddressInput)) { resultDiv.innerHTML = "Error: Invalid IP Address format."; return; } var ipBinary = ipToBinary(ipAddressInput); var subnetMaskDottedDecimal = ''; var cidrPrefix = ''; if (subnetMaskInput.startsWith('/')) { cidrPrefix = subnetMaskInput; subnetMaskDottedDecimal = cidrToDottedDecimal(subnetMaskInput); if (!subnetMaskDottedDecimal) { resultDiv.innerHTML = "Error: Invalid CIDR prefix."; return; } } else { if (!isValidIp(subnetMaskInput)) { resultDiv.innerHTML = "Error: Invalid Subnet Mask format."; return; } subnetMaskDottedDecimal = subnetMaskInput; cidrPrefix = dottedDecimalToCidr(subnetMaskInput); if (!cidrPrefix) { resultDiv.innerHTML = "Error: Invalid Subnet Mask (not a contiguous block of 1s)."; return; } } var subnetMaskBinary = ipToBinary(subnetMaskDottedDecimal); var numCidrBits = parseInt(cidrPrefix.substring(1), 10); var networkBinary = ''; for (var i = 0; i < 32; i++) { networkBinary += (ipBinary[i] === '1' && subnetMaskBinary[i] === '1') ? '1' : '0'; } var networkAddress = binaryToIp(networkBinary); var broadcastBinary = ''; for (var i = 0; i 0) { var networkInt = parseInt(networkBinary, 2); var firstUsableInt = networkInt + 1; firstUsableHost = binaryToIp(('00000000000000000000000000000000' + firstUsableInt.toString(2)).slice(-32)); } var lastUsableHost = 'N/A'; if (numberOfUsableHosts > 0) { var broadcastInt = parseInt(broadcastBinary, 2); var lastUsableInt = broadcastInt – 1; lastUsableHost = binaryToIp(('00000000000000000000000000000000' + lastUsableInt.toString(2)).slice(-32)); } var resultsHtml = "

Subnet Details:

"; resultsHtml += "IP Address: " + ipAddressInput + ""; resultsHtml += "Subnet Mask: " + subnetMaskDottedDecimal + " (" + cidrPrefix + ")"; resultsHtml += "Network Address: " + networkAddress + ""; resultsHtml += "Broadcast Address: " + broadcastAddress + ""; resultsHtml += "First Usable Host: " + firstUsableHost + ""; resultsHtml += "Last Usable Host: " + lastUsableHost + ""; resultsHtml += "Total Hosts: " + totalHosts + ""; resultsHtml += "Usable Hosts: " + numberOfUsableHosts + ""; resultDiv.innerHTML = resultsHtml; }

Understanding IP Subnetting

IP subnetting is a fundamental concept in computer networking that involves dividing a large network into smaller, more manageable subnetworks (subnets). This process helps in organizing IP addresses, improving network performance, enhancing security, and making more efficient use of available IP address space.

What is an IP Address?

An IP (Internet Protocol) address is a unique numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. IPv4 addresses, which are 32-bit numbers, are typically written in dotted-decimal notation (e.g., 192.168.1.10). An IP address is logically divided into two main parts:

• Network Portion: Identifies the specific network to which the device is connected. All devices on the same network share the same network portion.
• Host Portion: Identifies the specific device within that network.

The Role of the Subnet Mask

A subnet mask is a 32-bit number that distinguishes the network portion of an IP address from the host portion. Like an IP address, it's often represented in dotted-decimal notation (e.g., 255.255.255.0) or using CIDR (Classless Inter-Domain Routing) notation (e.g., /24).

• In a subnet mask, '1' bits indicate the network portion, and '0' bits indicate the host portion.
• For example, a subnet mask of 255.255.255.0 (which is 11111111.11111111.11111111.00000000 in binary) means the first 24 bits of an IP address are for the network, and the last 8 bits are for hosts. This is equivalent to /24 CIDR.

Key Subnetting Concepts

When you subnet a network, several important addresses and ranges are determined:

• Network Address: This is the first address in a subnet. It's used to identify the subnet itself and cannot be assigned to a host. All host bits are set to '0'.
• Broadcast Address: This is the last address in a subnet. It's used to send data to all devices within that specific subnet simultaneously and cannot be assigned to a host. All host bits are set to '1'.
• First Usable Host Address: The first IP address in the range that can be assigned to a device. It's always one greater than the network address.
• Last Usable Host Address: The last IP address in the range that can be assigned to a device. It's always one less than the broadcast address.
• Total Hosts: The total number of IP addresses within the subnet, including the network and broadcast addresses. This is calculated as 2^(number of host bits).
• Usable Hosts: The total count of IP addresses available for devices within the subnet. This is calculated as 2^(number of host bits) - 2 (subtracting the network and broadcast addresses). For /31 and /32 subnets, there are 0 usable hosts.

Why Subnet?

1. Efficiency: Reduces network traffic by confining broadcast domains to smaller subnets.
2. Security: Allows for the isolation of sensitive network segments.
3. Organization: Helps in logically structuring large networks, making them easier to manage and troubleshoot.
4. IP Address Conservation: While less critical with IPv6, subnetting helps in efficiently allocating IPv4 addresses, especially in scenarios where a large block of IPs is assigned but only smaller segments are needed in different locations.

How to Use the IP Subnet Calculator

Our IP Subnet Calculator simplifies the process of determining subnet details. Simply enter an IP address and its corresponding subnet mask (either in dotted-decimal format like 255.255.255.0 or CIDR notation like /24). The calculator will instantly provide you with:

• The Network Address
• The Broadcast Address
• The range of First and Last Usable Host Addresses
• The total number of hosts and usable hosts within that subnet

Example:

Let's say you enter an IP address 192.168.1.10 and a subnet mask of 255.255.255.0 (or /24).

The calculator would output:

• IP Address: 192.168.1.10
• Subnet Mask: 255.255.255.0 (/24)
• Network Address: 192.168.1.0
• Broadcast Address: 192.168.1.255
• First Usable Host: 192.168.1.1
• Last Usable Host: 192.168.1.254
• Total Hosts: 256
• Usable Hosts: 254

This means any device with an IP address from 192.168.1.1 to 192.168.1.254 can communicate within this subnet.