Network Bandwidth Calculator

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.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }

Network Bandwidth Calculator

Calculate file transfer time, required bandwidth, or actual throughput based on file size, link speed, and protocol overhead.

Calculation Mode

Transfer Time (given file size & bandwidth) Required Bandwidth (given file size & time) Actual Throughput (given bandwidth & overhead)

File / Data Size

Bytes (B) Kilobytes (KB) Megabytes (MB) Gigabytes (GB) Terabytes (TB)

Link / Bandwidth Speed

Kbps (kilobits/s) Mbps (megabits/s) Gbps (gigabits/s) KB/s MB/s GB/s

Desired Transfer Time

Seconds (s) Minutes (min) Hours (hr)

Protocol Overhead (%)

TCP/IP overhead is typically 3–10%. Set 0 for raw throughput.

Link Utilisation (%)

Realistic sustained utilisation of the link (typically 60–90%).

Calculate

function netUpdateMode() { var mode = document.getElementById("net-calc-mode").value; document.getElementById("net-group-filesize").style.display = "block"; document.getElementById("net-group-bandwidth").style.display = (mode === "required_bw") ? "none" : "block"; document.getElementById("net-group-time").style.display = (mode === "required_bw") ? "block" : "none"; document.getElementById("net-result").innerHTML = ""; }

function netFmt(val, unit) { if (val >= 1e12) return (val/1e12).toFixed(3) + " T" + unit; if (val >= 1e9) return (val/1e9).toFixed(3) + " G" + unit; if (val >= 1e6) return (val/1e6).toFixed(3) + " M" + unit; if (val >= 1e3) return (val/1e3).toFixed(3) + " K" + unit; return val.toFixed(3) + " " + unit; }

function netFmtTime(sec) { if (sec = 100) errors.push("Protocol overhead must be between 0 and 99%."); if (isNaN(utilPct) || utilPct 100) errors.push("Link utilisation must be between 1 and 100%.");

var fileSizeBytes = NaN, bwBps = NaN, timeSec = NaN;

if (mode === "transfer_time" || mode === "throughput" || mode === "required_bw") { var fsVal = parseFloat(document.getElementById("net-filesize").value); var fsUnit = parseFloat(document.getElementById("net-filesize-unit").value); if (isNaN(fsVal) || fsVal 0) { res.innerHTML = "Please fix the following:" + errors.map(function(e){ return ""; }).join("") + ""; return; }

// --- Core Calculations --- // overheadFactor: fraction of bandwidth consumed by overhead var overheadFactor = overheadPct / 100; var utilisationFactor = utilPct / 100;

// Effective bytes/s available for payload // effectiveBw = linkBw * utilisation * (1 - overhead) var html = "";

if (mode === "transfer_time") { // Transfer Time = (File Size in bits) / (Effective bandwidth in bits/s) // bwBps is already bytes/s (from unit conversion) var effectiveBwBytesPerSec = bwBps * utilisationFactor * (1 - overheadFactor); var fileSizeBits = fileSizeBytes * 8; var effectiveBwBitsPerSec = effectiveBwBytesPerSec * 8; var transferTimeSec = fileSizeBytes / effectiveBwBytesPerSec;

html = "### Transfer Time Results " + "File Size" + netFmt(fileSizeBytes,"B") + " (" + netFmt(fileSizeBits,"bits") + ")" + "Raw Link Speed" + netFmt(bwBps8,"bps") + " (" + netFmt(bwBps,"B/s") + ")" + "Protocol Overhead" + overheadPct.toFixed(1) + "%" + "Link Utilisation" + utilPct.toFixed(1) + "%" + "Effective Throughput" + netFmt(effectiveBwBitsPerSec,"bps") + " (" + netFmt(effectiveBwBytesPerSec,"B/s") + ")" + "Estimated Transfer Time*" + netFmtTime(transferTimeSec) + "" + "";

// Bonus: show at different utilisation levels html += "#### Transfer Time at Different Utilisation Levels " + "UtilisationEffective SpeedTransfer Time"; [100,90,80,70,60,50].forEach(function(u){ var eff = bwBps * (u/100) * (1 - overheadFactor); var t = fileSizeBytes / eff; var row = (u === Math.round(utilPct)) ? " class='calc-highlight'" : ""; html += "" + u + "%" + netFmt(eff*8,"bps") + "" + netFmtTime(t) + ""; }); html += "";

} else if (mode === "required_bw") { // Required Bandwidth = File Size / (Transfer Time * utilisation * (1 - overhead)) var requiredEffBytesPerSec = fileSizeBytes / timeSec; var requiredRawBytesPerSec = requiredEffBytesPerSec / (utilisationFactor * (1 - overheadFactor)); var requiredRawBitsPerSec = requiredRawBytesPerSec * 8;

html = "### Required Bandwidth Results " + "File Size" + netFmt(fileSizeBytes,"B") + " (" + netFmt(fileSizeBytes8,"bits") + ")" + "Desired Transfer Time" + netFmtTime(timeSec) + "" + "Protocol Overhead" + overheadPct.toFixed(1) + "%" + "Link Utilisation" + utilPct.toFixed(1) + "%" + "Required Effective Throughput" + netFmt(requiredEffBytesPerSec8,"bps") + "" + "Required Raw Link Speed" + netFmt(requiredRawBitsPerSec,"bps") + " (" + netFmt(requiredRawBytesPerSec,"B/s") + ")" + "";

// Common link speeds comparison var commonLinks = [ {name:"DSL 10 Mbps", bps:10e6}, {name:"Cable 100 Mbps", bps:100e6}, {name:"Fiber 1 Gbps", bps:1e9}, {name:"Fiber 10 Gbps", bps:10e9}, {name:"100 Gbps", bps:100e9} ]; html += "#### Common Link Speed Comparison " + "Link TypeSpeedSufficient?Transfer Time"; commonLinks.forEach(function(lk){ var eff = (lk.bps/8) * utilisationFactor * (1 - overheadFactor); var t = fileSizeBytes / eff; var ok = lk.bps >= requiredRawBitsPerSec ? "✅ Yes" : "❌ No"; html += "" + lk.name + "" + netFmt(lk.bps,"bps") + "" + ok + "" + netFmtTime(t) + ""; }); html += "";

} else { // throughput // Actual Throughput = Link Speed * Utilisation * (1 - Overhead) var rawBytesPerSec = bwBps; var rawBitsPerSec = rawBytesPerSec * 8; var afterUtilBytes = rawBytesPerSec * utilisationFactor; var effectiveBytes = afterUtilBytes * (1 - overheadFactor); var effectiveBits = effectiveBytes * 8; var overheadBytes = afterUtilBytes * overheadFactor; var unusedBytes = rawBytesPerSec * (1 - utilisationFactor); var transferTimeSec2 = fileSizeBytes / effectiveBytes;

html = "### Throughput Analysis Results " + "Raw Link Speed" + netFmt(rawBitsPerSec,"bps") + " (" + netFmt(rawBytesPerSec,"B/s") + ")" + "Link Utilisation (" + utilPct.toFixed(1) + "%)" + netFmt(afterUtilBytes8,"bps") + " (" + netFmt(afterUtilBytes,"B/s") + ")" + "Protocol Overhead (" + overheadPct.toFixed(1) + "%)−" + netFmt(overheadBytes8,"bps") + " (" + netFmt(overheadBytes,"B/s") + ")" + "Effective Payload Throughput" + netFmt(effectiveBits,"bps") + " (" + netFmt(effectiveBytes,"B/s") + ")" + "Unused Capacity" + netFmt(unusedBytes8,"bps") + " (" + ((1-utilisationFactor)100).toFixed(1) + "% of link)" + "Overall Efficiency" + (effectiveBytes/rawBytesPerSec100).toFixed(2) + "% of raw link speed" + "File Size" + netFmt(fileSizeBytes,"B") + "" + "Estimated Transfer Time*" + netFmtTime(transferTimeSec2) + "" + ""; }

res.innerHTML = html; }

#### Formulas Used

Transfer Time: Transfer Time = File Size (bytes) ÷ Effective Throughput (B/s) Effective Throughput = Link Speed × Link Utilisation × (1 − Overhead Fraction)

Required Bandwidth: Required Raw Speed = File Size ÷ (Transfer Time × Utilisation × (1 − Overhead))

Actual Throughput: Effective Throughput = Link Speed × Utilisation × (1 − Overhead) Overall Efficiency (%) = Effective Throughput ÷ Raw Link Speed × 100

Unit Conversions: 1 byte = 8 bits | 1 KB = 1,024 B | 1 MB = 1,048,576 B | 1 Mbps = 1,000,000 bits/s (SI) | 1 MB/s = 8 Mbps

#### Assumptions & References

Reference: Tanenbaum & Wetherall, Computer Networks, 5th ed.; Forouzan, Data Communications and Networking, 5th ed.

Network Bandwidth Calculator

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Network Bandwidth Calculator

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