Network Bandwidth & Throughput Calculator

ANA›Life Services Authority›National Calculator Authority›Network Bandwidth & Throughput Calculator

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Network Bandwidth & Throughput Calculator

Calculate theoretical bandwidth, actual throughput, file transfer time, and network efficiency based on connection parameters and protocol overhead.

Link Bandwidth

bps Kbps Mbps Gbps Tbps

File / Data Size

Byte KB MB GB TB

Protocol Overhead (%)

TCP/IP overhead ~20%, Ethernet ~7%, combined ~25%

Link Utilization (%)

Practical max utilization before congestion

Round-Trip Latency (ms)

Ping / RTT in milliseconds

TCP Window Size

Bytes KB MB

Default TCP: 65535 B; with scaling up to 1 GB

Calculate

function netCalc() { const errEl = document.getElementById('net-error'); const resEl = document.getElementById('net-result'); errEl.style.display = 'none'; resEl.style.display = 'none';

// --- gather inputs --- const bwRaw = parseFloat(document.getElementById('net-bandwidth').value); const bwUnit = parseFloat(document.getElementById('net-bandwidth-unit').value); const fsRaw = parseFloat(document.getElementById('net-file-size').value); const fsUnit = parseFloat(document.getElementById('net-file-unit').value); const overhead = parseFloat(document.getElementById('net-overhead').value); const utilization = parseFloat(document.getElementById('net-utilization').value); const latencyMs = parseFloat(document.getElementById('net-latency').value); const winRaw = parseFloat(document.getElementById('net-window').value); const winUnit = parseFloat(document.getElementById('net-window-unit').value);

// --- validation --- const errors = []; if (isNaN(bwRaw) || bwRaw 0."); if (isNaN(fsRaw) || fsRaw = 100) errors.push("Protocol Overhead must be between 0 and 99%."); if (isNaN(utilization) || utilization 100) errors.push("Link Utilization must be between 1 and 100%."); if (isNaN(latencyMs) || latencyMs 0.");

if (errors.length) { errEl.innerHTML = errors.join(''); errEl.style.display = 'block'; return; }

// --- core calculations --- // Bandwidth in bps const bwBps = bwRaw * bwUnit;

// File size in bits const fileBits = fsRaw * fsUnit;

// Effective throughput (bps) after overhead and utilization // Throughput = Bandwidth × Utilization% × (1 − Overhead%) const throughputBps = bwBps * (utilization / 100) * (1 - overhead / 100);

// Transfer time (seconds) = File size (bits) / Throughput (bps) const transferTimeSec = fileBits > 0 ? fileBits / throughputBps : 0;

// Bandwidth-Delay Product (BDP) in bits // BDP = Bandwidth (bps) × RTT (s) const rttSec = latencyMs / 1000; const bdpBits = bwBps * rttSec; const bdpBytes = bdpBits / 8;

// TCP Throughput limited by window size (Mathis formula simplified) // Max TCP Throughput = Window Size (bits) / RTT (s) const windowBits = winRaw * winUnit * 8; const tcpMaxThroughputBps = rttSec > 0 ? windowBits / rttSec : Infinity;

// Effective TCP throughput = min(link throughput, TCP window-limited throughput) const effectiveTcpBps = Math.min(throughputBps, tcpMaxThroughputBps);

// TCP transfer time const tcpTransferTimeSec = fileBits > 0 ? fileBits / effectiveTcpBps : 0;

// Network efficiency const efficiency = (1 - overhead / 100) * (utilization / 100) * 100;

// --- helpers --- function fmtBps(bps) { if (bps >= 1e12) return (bps/1e12).toFixed(3) + ' Tbps'; if (bps >= 1e9) return (bps/1e9).toFixed(3) + ' Gbps'; if (bps >= 1e6) return (bps/1e6).toFixed(3) + ' Mbps'; if (bps >= 1e3) return (bps/1e3).toFixed(3) + ' Kbps'; return bps.toFixed(2) + ' bps'; } function fmtBytes(bytes) { if (bytes >= 1e12) return (bytes/1e12).toFixed(3) + ' TB'; if (bytes >= 1e9) return (bytes/1e9).toFixed(3) + ' GB'; if (bytes >= 1e6) return (bytes/1e6).toFixed(3) + ' MB'; if (bytes >= 1e3) return (bytes/1e3).toFixed(3) + ' KB'; return bytes.toFixed(2) + ' Bytes'; } function fmtTime(sec) { if (sec === 0) return '0 s'; if (sec

Theoretical Bandwidth ${fmtBps(bwBps)}

Effective Throughput (overhead + utilization) ${fmtBps(throughputBps)}

TCP Window-Limited Max Throughput ${rttSec > 0 ? fmtBps(tcpMaxThroughputBps) : 'N/A (RTT = 0)'}

Effective TCP Throughput

${fmtBps(effectiveTcpBps)} ${tcpLimited ? '⚠ window-limited' : '✓'}

Bandwidth-Delay Product (BDP) ${fmtBytes(bdpBytes)} (${(bdpBits/1e6).toFixed(3)} Mb)

Network Efficiency ${efficiency.toFixed(2)}%

${fileBits > 0 ? `

Transfer Time (effective throughput) ${fmtTime(transferTimeSec)}

Transfer Time (TCP-limited) ${fmtTime(tcpTransferTimeSec)} ` : ''}

${tcpLimited && rttSec > 0 ? ` ⚠ TCP Window Bottleneck: Your TCP window size (${fmtBytes(winRaw*winUnit)}) is smaller than the Bandwidth-Delay Product (${fmtBytes(bdpBytes)}). Increase the TCP window size to fully utilize the link.

: ''}; resEl.style.display = 'block'; }

#### Formulas Used

Effective Throughput: Throughput = Bandwidth × (Utilization / 100) × (1 − Overhead / 100)

Transfer Time: Transfer Time = File Size (bits) / Throughput (bps)

Bandwidth-Delay Product (BDP): BDP = Bandwidth (bps) × RTT (s) Represents the amount of data "in flight" on the network at any moment — the pipe volume.

TCP Maximum Throughput (window-limited): TCP Throughput_max = Window Size (bits) / RTT (s) Derived from the TCP sliding window mechanism. If Window Size < BDP, TCP cannot fully saturate the link.

Network Efficiency: Efficiency (%) = (1 − Overhead / 100) × (Utilization / 100) × 100

#### Assumptions & References

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References

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