Calculator Subnet Ip

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Advanced IP Subnet Calculator

Calculate network ranges, broadcast addresses, and usable hosts instantly.

/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 (255.254.0.0) /14 (255.252.0.0) /13 (255.248.0.0) /12 (255.240.0.0) /11 (255.224.0.0) /10 (255.192.0.0) /9 (255.128.0.0) /8 (255.0.0.0) /7 (254.0.0.0) /6 (252.0.0.0) /5 (248.0.0.0) /4 (240.0.0.0) /3 (224.0.0.0) /2 (192.0.0.0) /1 (128.0.0.0)
Network Address:
Broadcast Address:
First Usable Host:
Last Usable Host:
Total Hosts:
Usable Hosts:
Subnet Mask:
Wildcard Mask:
CIDR Notation:

Understanding IP Subnetting

An IP Subnet Calculator is a critical tool for network administrators and engineers. It allows you to take a single IP address and a subnet mask (or CIDR prefix) and determine the boundaries of that specific network. Subnetting is the process of dividing a large network into smaller, manageable sub-networks (subnets).

Why is Subnetting Important?

Subnetting serves several vital functions in modern networking:

  • Efficiency: It prevents IP address waste by allocating only the necessary number of addresses to a specific segment.
  • Security: By isolating network segments, you can control traffic flow between departments or zones using firewalls and routers.
  • Performance: It reduces broadcast traffic. In a large flat network, broadcast packets reach every device, slowing down the network. Subnetting confines these broadcasts to smaller groups.
Example Calculation:
If you have an IP of 192.168.1.10 with a /24 mask (255.255.255.0):
• The Network Address is 192.168.1.0
• The Broadcast Address is 192.168.1.255
• Usable IPs range from 192.168.1.1 to 192.168.1.254 (254 hosts).

Key Terms to Know

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 devices on that subnet simultaneously.

CIDR (Classless Inter-Domain Routing): A method for allocating IP addresses and IP routing. It replaces the old "Class A, B, C" system with a more flexible prefix notation (e.g., /24).

Usable Hosts: The number of IP addresses that can actually be assigned to devices (computers, servers, printers). This is calculated as (2^n) – 2, where 'n' is the number of host bits. We subtract 2 for the network and broadcast addresses.

function calculateSubnet() { var ipStr = document.getElementById('ipAddress').value.trim(); var cidr = parseInt(document.getElementById('cidrPrefix').value); // Validate IP format var ipParts = ipStr.split('.'); if (ipParts.length !== 4) { alert("Please enter a valid IPv4 address (e.g., 192.168.1.1)"); return; } var ipInt = 0; for (var i = 0; i < 4; i++) { var octet = parseInt(ipParts[i]); if (isNaN(octet) || octet 255) { alert("Each octet of the IP address must be between 0 and 255."); return; } ipInt = (ipInt <>> 0; // Calculate Mask var maskInt = 0; if (cidr > 0) { maskInt = (0xFFFFFFFF <>> 0; } else { maskInt = 0; } var wildcardInt = (~maskInt) >>> 0; var networkInt = (ipInt & maskInt) >>> 0; var broadcastInt = (networkInt | wildcardInt) >>> 0; // Host calculations var totalHosts = Math.pow(2, (32 – cidr)); var usableHosts = (cidr >= 31) ? 0 : totalHosts – 2; if (cidr === 32) usableHosts = 1; // Special case for /32 host route if (cidr === 31) usableHosts = 2; // Special case for P2P links (RFC 3021) // Result formatting document.getElementById('resNetwork').innerText = intToIp(networkInt); document.getElementById('resBroadcast').innerText = intToIp(broadcastInt); document.getElementById('resMask').innerText = intToIp(maskInt); document.getElementById('resWildcard').innerText = intToIp(wildcardInt); document.getElementById('resCIDR').innerText = "/" + cidr; document.getElementById('resTotalHosts').innerText = totalHosts.toLocaleString(); document.getElementById('resUsableHosts').innerText = (usableHosts < 0 ? 0 : usableHosts).toLocaleString(); if (cidr >> 24) + '.' + ((int >> 16) & 255) + '.' + ((int >> 8) & 255) + '.' + (int & 255) ); }

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