Ip Range Calculator

IP Range Calculator

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

Enter either CIDR or Subnet Mask. CIDR takes precedence if both are entered.

// Helper function to validate an IP address format function isValidIpAddress(ipStr) { var parts = ipStr.split('.'); if (parts.length !== 4) { return false; } for (var i = 0; i < parts.length; i++) { var part = parseInt(parts[i], 10); if (isNaN(part) || part 255) { return false; } } return true; } // Helper function to convert a dotted-decimal IP to a 32-bit unsigned integer function parseIpToLong(ipStr) { var parts = ipStr.split('.'); return ((parseInt(parts[0], 10) << 24) | (parseInt(parts[1], 10) << 16) | (parseInt(parts[2], 10) <>> 0; // Use >>> 0 to ensure unsigned 32-bit } // Helper function to convert a 32-bit unsigned integer back to a dotted-decimal IP function longToIp(longIp) { return ((longIp >>> 24) & 0xFF) + '.' + ((longIp >>> 16) & 0xFF) + '.' + ((longIp >>> 8) & 0xFF) + '.' + (longIp & 0xFF); } // Helper function to calculate CIDR from a subnet mask long function calculateCidrFromMask(maskLong) { var cidr = 0; // Check for all 1s followed by all 0s // A valid mask, when inverted, should be all 0s followed by all 1s (or all 0s for /32) // e.g., /24 mask: 11111111.11111111.11111111.00000000 // Inverted: 00000000.00000000.00000000.11111111 // This pattern (0…01…1) has the property that (invertedMask + 1) & invertedMask == 0 // Except for /32 where invertedMask is 0. var invertedMaskLong = (~maskLong) >>> 0; if (maskLong === 0xFFFFFFFF) { // /32 mask cidr = 32; } else if (maskLong === 0x00000000) { // 0.0.0.0 mask cidr = 0; } else if ((invertedMaskLong & (invertedMaskLong + 1)) === 0) { // It's a valid mask pattern, now count the 1s var tempMask = maskLong; while ((tempMask & 0x80000000) !== 0 && cidr < 32) { cidr++; tempMask = (tempMask <>> 0; } } else { return -1; // Invalid mask pattern } return cidr; } function calculateIpRange() { var ipAddressStr = document.getElementById("ipAddressInput").value.trim(); var cidrStr = document.getElementById("cidrInput").value.trim(); var subnetMaskStr = document.getElementById("subnetMaskInput").value.trim(); var resultDiv = document.getElementById("resultDiv"); resultDiv.innerHTML = ""; // Clear previous results if (!isValidIpAddress(ipAddressStr)) { resultDiv.innerHTML = "Error: Please enter a valid IP Address (e.g., 192.168.1.0)."; return; } var ipLong = parseIpToLong(ipAddressStr); var subnetMaskLong; var cidr; // Determine CIDR and subnetMaskLong if (cidrStr !== "" && !isNaN(parseInt(cidrStr, 10))) { var parsedCidr = parseInt(cidrStr, 10); if (parsedCidr >= 0 && parsedCidr <= 32) { cidr = parsedCidr; subnetMaskLong = (0xFFFFFFFF <>> 0; } else { resultDiv.innerHTML = "Error: CIDR value must be between 0 and 32."; return; } } else if (subnetMaskStr !== "" && isValidIpAddress(subnetMaskStr)) { subnetMaskLong = parseIpToLong(subnetMaskStr); cidr = calculateCidrFromMask(subnetMaskLong); if (cidr === -1) { resultDiv.innerHTML = "Error: Invalid subnet mask pattern. A subnet mask must consist of a contiguous block of ones followed by a contiguous block of zeros."; return; } } else { resultDiv.innerHTML = "Error: Please enter a valid CIDR (0-32) or a valid Subnet Mask (e.g., 255.255.255.0)."; return; } var networkAddressLong = (ipLong & subnetMaskLong) >>> 0; var hostBits = 32 – cidr; var broadcastAddressLong; if (hostBits === 0) { // /32 broadcastAddressLong = networkAddressLong; } else { broadcastAddressLong = (networkAddressLong | ((1 <>> 0; } var firstUsableIpLong = 0; var lastUsableIpLong = 0; var totalHosts = 0; var usableHosts = 0; if (hostBits === 0) { // /32 firstUsableIpLong = networkAddressLong; lastUsableIpLong = networkAddressLong; totalHosts = 1; usableHosts = 1; } else if (hostBits === 1) { // /31 firstUsableIpLong = networkAddressLong; // Network address lastUsableIpLong = broadcastAddressLong; // Broadcast address totalHosts = 2; usableHosts = 0; // No usable hosts in /31 } else { // hostBits >= 2 firstUsableIpLong = networkAddressLong + 1; lastUsableIpLong = broadcastAddressLong – 1; totalHosts = Math.pow(2, hostBits); usableHosts = totalHosts – 2; } // Convert back to dotted decimal var networkAddress = longToIp(networkAddressLong); var broadcastAddress = longToIp(broadcastAddressLong); var firstUsableIp = longToIp(firstUsableIpLong); var lastUsableIp = longToIp(lastUsableIpLong); var calculatedSubnetMask = longToIp(subnetMaskLong); var output = "

IP Range Details:

"; output += "IP Address: " + ipAddressStr + ""; output += "Subnet Mask: " + calculatedSubnetMask + ""; output += "CIDR: /" + cidr + ""; output += "Network Address: " + networkAddress + ""; output += "Broadcast Address: " + broadcastAddress + ""; if (usableHosts > 0) { output += "First Usable Host IP: " + firstUsableIp + ""; output += "Last Usable Host IP: " + lastUsableIp + ""; } else { output += "Usable Host IP Range: None (for /31 and /32 networks, or if network/broadcast are the same)"; } output += "Total Hosts: " + totalHosts + ""; output += "Usable Hosts: " + usableHosts + ""; resultDiv.innerHTML = output; }

Understanding IP Ranges and Subnetting

An IP Range Calculator is an essential tool for network administrators, IT professionals, and anyone involved in network planning and management. It helps in understanding how IP addresses are structured and how they are divided into networks and subnets.

What is an IP Address?

An Internet Protocol (IP) address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. In IPv4, these addresses are 32-bit numbers, typically represented in dotted-decimal notation (e.g., 192.168.1.1), where four numbers (octets) are separated by dots, each ranging from 0 to 255.

The Role of a Subnet Mask

A subnet mask is a 32-bit number that divides an IP address into two parts: the network portion and the host portion. It works by masking the IP address. Where there is a '1' in the subnet mask, the corresponding bit in the IP address belongs to the network portion. Where there is a '0', it belongs to the host portion.

For example, a common subnet mask is 255.255.255.0. In binary, this is 11111111.11111111.11111111.00000000. This mask indicates that the first three octets of an IP address identify the network, and the last octet identifies a specific host within that network.

CIDR (Classless Inter-Domain Routing)

CIDR is a method for allocating IP addresses and routing IP packets. It was introduced to replace the old classful networking system (Class A, B, C) and improve IP address utilization. CIDR notation simplifies the representation of a subnet mask by indicating the number of bits in the network portion of the IP address.

Instead of writing 255.255.255.0, you can use /24, which means the first 24 bits of the IP address are for the network, and the remaining 8 bits are for hosts. This notation is concise and widely used.

Key Components of an IP Range

When you calculate an IP range, several important addresses and values are determined:

• Network Address: This is the first IP address in a given range. It identifies the network itself and is typically not assigned to a host. All host bits are set to zero.
• Broadcast Address: This is the last IP address in a given range. It is used to send data to all devices within that specific network segment. All host bits are set to one.
• First Usable Host IP: This is the first IP address within the range that can be assigned to a device (e.g., a computer, server, or router interface). It is always one greater than the network address.
• Last Usable Host IP: This is the last IP address within the range that can be assigned to a device. It is always one less than the broadcast address.
• Total Hosts: The total number of IP addresses available within the defined network range, including the network and broadcast addresses.
• Usable Hosts: The number of IP addresses that can actually be assigned to devices. This is typically the total hosts minus two (for the network and broadcast addresses). For very small subnets like /31 or /32, the number of usable hosts can be 0 or 1.

How the Calculator Works

The calculator takes an IP address and either a CIDR value or a subnet mask. It then performs bitwise logical operations to determine the network and broadcast addresses. For instance, the network address is found by performing a bitwise AND operation between the IP address and the subnet mask. The broadcast address is found by performing a bitwise OR operation between the network address and the inverted subnet mask (or host portion mask).

Practical Applications

IP range calculation is crucial for:

• Network Design: Planning how to segment a large network into smaller, more manageable subnets.
• IP Address Management (IPAM): Efficiently allocating and tracking IP addresses to avoid conflicts and ensure optimal use.
• Security: Configuring firewalls and access control lists (ACLs) to permit or deny traffic based on IP ranges.
• Troubleshooting: Identifying network boundaries and potential routing issues.
• Resource Allocation: Ensuring that each department or segment of an organization has enough IP addresses for its devices.

Example Usage

Let's say you have an IP address 192.168.1.0 and a CIDR of /24. The calculator would determine:

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

This calculator simplifies these complex calculations, providing quick and accurate results for your networking needs.