Understanding IP addresses, subnet masks, and CIDR notation is fundamental for anyone working with computer networks. This IP Range Calculator helps you quickly determine key network parameters based on an IP address and a subnet mask or CIDR value.
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. It serves two main functions: host or network interface identification and location addressing. IPv4 addresses are 32-bit numbers, typically represented in dotted-decimal notation (e.g., 192.168.1.1), where each of the four numbers (octets) ranges from 0 to 255.
What is a Subnet Mask?
A subnet mask is a 32-bit number that divides an IP address into two parts: the network address and the host address. It works by "masking" the IP address. The bits in the subnet mask that are set to '1' indicate the network portion of the IP address, while the bits set to '0' indicate the host portion. For example, a subnet mask of 255.255.255.0 means the first three octets define the network, and the last octet defines the host.
Subnetting allows a network administrator to divide a large network into smaller, more efficient sub-networks (subnets). This improves network performance, enhances security, and makes network management easier.
What is CIDR Notation?
Classless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and for IP routing. It was introduced to replace the old classful network addressing system (Class A, B, C). CIDR notation simplifies the representation of a subnet mask by appending a slash (/) followed by the number of bits in the network portion of the address. For instance, /24 is equivalent to a subnet mask of 255.255.255.0, as there are 24 '1' bits in the mask.
Key Network Parameters Calculated:
Network Address: The first address in a given network range. It's used to identify the network itself and cannot be assigned to a host. All host bits are zero.
Broadcast Address: The last address in a given network range. Messages sent to this address are delivered to all devices on that network segment. All host bits are one.
First Usable IP: The first IP address in the range that can be assigned to a host device. This is typically the Network Address + 1.
Last Usable IP: The last IP address in the range that can be assigned to a host device. This is typically the Broadcast Address – 1.
Total Number of Hosts: The total count of IP addresses available within the network range. This includes the network and broadcast addresses.
Number of Usable Hosts: The number of IP addresses that can actually be assigned to devices. This is typically the Total Number of Hosts – 2 (excluding the network and broadcast addresses).
How to Use the Calculator:
Enter an IP address and either a subnet mask or a CIDR value. The calculator will then provide all the relevant network details.
Example:
Let's say you have an IP address 192.168.10.15 and a subnet mask of 255.255.255.192 (which is /26 CIDR).
Input IP Address:192.168.10.15
Input Subnet Mask:255.255.255.192 (or CIDR: /26)
The calculator would output:
Network Address:192.168.10.0
Broadcast Address:192.168.10.63
First Usable IP:192.168.10.1
Last Usable IP:192.168.10.62
Total Hosts:64
Usable Hosts:62
Subnet Mask:255.255.255.192
CIDR:/26
IP Range Calculator
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function ipToLong(ipAddress) {
var parts = ipAddress.split('.');
if (parts.length !== 4) return NaN;
var longIp = 0;
for (var i = 0; i < 4; i++) {
var octet = parseInt(parts[i], 10);
if (isNaN(octet) || octet 255) return NaN;
longIp = (longIp <>> 0; // Ensure unsigned 32-bit
}
function longToIp(longIp) {
return ((longIp >>> 24) & 0xFF) + '.' +
((longIp >>> 16) & 0xFF) + '.' +
((longIp >>> 8) & 0xFF) + '.' +
(longIp & 0xFF);
}
function cidrToMaskLong(cidr) {
var numCidr = parseInt(cidr, 10);
if (isNaN(numCidr) || numCidr 32) return NaN;
if (numCidr === 0) return 0;
var mask = -1 <>> 0; // Ensure unsigned 32-bit
}
function maskLongToCidr(maskLong) {
var cidr = 0;
var tempMask = maskLong >>> 0; // Ensure unsigned
// Check for contiguous 1s from left
for (var i = 0; i >> (31 – i)) & 1) {
cidr++;
} else {
// If we find a 0, all subsequent bits must be 0 for a valid mask
if (tempMask << (i + 1) !== 0) {
return -1; // Invalid mask (non-contiguous 1s)
}
break;
}
}
return cidr;
}
function isValidIp(ipAddress) {
var regex = /^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/;
return regex.test(ipAddress);
}
function isValidSubnetMask(maskString) {
if (!isValidIp(maskString)) return false;
var maskLong = ipToLong(maskString);
var cidr = maskLongToCidr(maskLong);
return cidr !== -1; // -1 indicates an invalid mask pattern
}
function isValidCidr(cidrString) {
if (!cidrString || cidrString.length = 0 && numCidr >> 0;
var broadcastAddressLong = (networkAddressLong | (~subnetMaskLong)) >>> 0;
var numHosts = Math.pow(2, (32 – calculatedCidr));
var usableHosts = numHosts – 2;
var firstUsableIpLong = 0;
var lastUsableIpLong = 0;
if (usableHosts > 0) {
firstUsableIpLong = networkAddressLong + 1;
lastUsableIpLong = broadcastAddressLong – 1;
}
var output = '