Fydler UtilityBelt - CIDR Calculator (IP Subnetting Tool)

CIDR Calculator

Time & Networking Tool

IP Address / CIDR

Enter an IP address in CIDR notation (e.g., 192.168.1.1/24) to calculate network details, host ranges, and broadcast addresses.

lucide.createIcons(); const ipInput = document.getElementById('ip-input'); const calculateBtn = document.getElementById('calculate-btn'); calculateBtn.addEventListener('click', calculateCIDR); ipInput.addEventListener('keypress', (e) => { if (e.key === 'Enter') calculateCIDR(); }); function ipToInt(ip) { return ip.split('.').reduce((int, octet) => (int << 8) + parseInt(octet), 0) >>> 0; } function intToIp(int) { return [ (int >>> 24) & 0xFF, (int >>> 16) & 0xFF, (int >>> 8) & 0xFF, int & 0xFF ].join('.'); } function intToBinary(int) { return int.toString(2).padStart(32, '0').match(/.{8}/g).join('.'); } function calculateCIDR() { const input = document.getElementById('ip-input').value.trim(); if (!input) return; const parts = input.split('/'); const ipStr = parts[0]; const cidr = parts.length > 1 ? parseInt(parts[1]) : 32; if (isNaN(cidr) || cidr < 0 || cidr > 32) { alert('Invalid CIDR prefix'); return; } // Validate IP const ipPattern = /^(\d{1,3}\.){3}\d{1,3}$/; if (!ipPattern.test(ipStr)) { alert('Invalid IP address'); return; } const octets = ipStr.split('.'); if (octets.some(o => parseInt(o) > 255)) { alert('Invalid IP address'); return; } const ip = ipToInt(ipStr); const mask = (cidr === 0 ? 0 : (~0 << (32 - cidr))) >>> 0; const network = (ip & mask) >>> 0; const broadcast = (network | ~mask) >>> 0; const wildcard = (~mask) >>> 0; let firstHost, lastHost, totalHosts; if (cidr === 32) { firstHost = network; lastHost = network; totalHosts = 1; } else if (cidr === 31) { firstHost = network; lastHost = broadcast; totalHosts = 2; } else { firstHost = network + 1; lastHost = broadcast - 1; totalHosts = Math.max(0, broadcast - network - 1); } // Update UI document.getElementById('res-network').textContent = intToIp(network) + ' /' + cidr; document.getElementById('res-broadcast').textContent = intToIp(broadcast); document.getElementById('res-range').textContent = cidr >= 31 ? `${intToIp(firstHost)} - ${intToIp(lastHost)}` : `${intToIp(firstHost)} - ${intToIp(lastHost)}`; document.getElementById('res-hosts').textContent = totalHosts.toLocaleString(); document.getElementById('res-mask').textContent = intToIp(mask); document.getElementById('res-wildcard').textContent = intToIp(wildcard); document.getElementById('bin-ip').textContent = intToBinary(ip); document.getElementById('bin-mask').textContent = intToBinary(mask); document.getElementById('bin-network').textContent = intToBinary(network); document.getElementById('results').classList.remove('hidden'); }

CIDR Calculator

Binary Representation