The amount of data sent from your GPU to your monitor is determined by four primary variables: resolution, refresh rate, color depth, and chroma subsampling. To find the raw data rate, we use the following formula:
Formula:(Horizontal Pixels × Vertical Pixels) × Refresh Rate × Color Channels (3) × Bits Per Channel × Chroma Ratio
However, real-world signals require "Blanking Intervals"—short pauses between frames and lines originally used for CRT electron beams but still used today for synchronization. We apply a standard timing factor (usually CVT-RB) of roughly 8% to 10% on top of the raw pixel data to determine the actual required bandwidth.
Key Factors Affecting Bandwidth
Resolution: The more pixels on screen (e.g., 4K vs 1080p), the more data must be pushed per frame.
Refresh Rate: Doubling your Hz (e.g., 60Hz to 120Hz) exactly doubles the bandwidth requirement.
Color Depth: 8-bit color uses 24 bits per pixel (8 bits each for Red, Green, and Blue). 10-bit HDR uses 30 bits per pixel, requiring 25% more bandwidth.
Chroma Subsampling: 4:2:0 subsampling reduces the color information to save bandwidth (commonly used in streaming and ultra-high-res TV signals) while 4:4:4 provides full color detail.
Real-World Examples
Resolution
Refresh Rate
Color Depth
Est. Bandwidth
1080p (1920×1080)
60Hz
8-bit
~3.20 Gbps
1440p (2560×1440)
144Hz
8-bit
~14.08 Gbps
4K (3840×2160)
60Hz
10-bit
~12.54 Gbps
4K (3840×2160)
144Hz
10-bit
~30.00 Gbps
Standard Interface Limits
Knowing your required bandwidth is essential for choosing the right cable. Here are the maximum data rate capacities for common standards:
HDMI 1.4: 8.16 Gbps
HDMI 2.0: 14.4 Gbps
HDMI 2.1: 42.6 Gbps
DisplayPort 1.2: 17.28 Gbps
DisplayPort 1.4: 25.92 Gbps
DisplayPort 2.1 (UHBR20): 77.37 Gbps
function calculateBandwidth() {
var w = parseFloat(document.getElementById('resWidth').value);
var h = parseFloat(document.getElementById('resHeight').value);
var r = parseFloat(document.getElementById('refreshRate').value);
var depth = parseFloat(document.getElementById('colorDepth').value);
var chroma = parseFloat(document.getElementById('chroma').value);
if (isNaN(w) || isNaN(h) || isNaN(r)) {
alert("Please enter valid numerical values for resolution and refresh rate.");
return;
}
// Calculation: Pixels * Refresh Rate * (BitsPerChannel * 3 channels) * Chroma Factor
// Adding 8% overhead for CVT-RB (Coordinated Video Timings-Reduced Blanking)
var rawPixelClock = w * h * r;
var bitsPerPixel = depth * 3 * chroma;
var netDataRateBps = rawPixelClock * bitsPerPixel * 1.08; // 1.08 accounts for blanking
var netGbps = netDataRateBps / 1000000000;
// Transmission rate includes encoding overhead (8b/10b for older standards, 128b/132b for newer)
// We display the data rate (payload) as that's what cable specs usually refer to
var transRate = netGbps * 1.25; // General estimate for 8b/10b encoding
document.getElementById('dataRate').innerText = netGbps.toFixed(2);
document.getElementById('transRate').innerText = transRate.toFixed(2);
// Update Compatibility
var compatList = document.getElementById('compatList');
compatList.innerHTML = "";
var interfaces = [
{ name: "HDMI 1.4", limit: 8.16 },
{ name: "HDMI 2.0", limit: 14.4 },
{ name: "HDMI 2.1", limit: 42.6 },
{ name: "DisplayPort 1.2", limit: 17.28 },
{ name: "DisplayPort 1.4", limit: 25.92 },
{ name: "DisplayPort 2.1", limit: 77.3 }
];
for (var i = 0; i < interfaces.length; i++) {
var statusClass = (netGbps <= interfaces[i].limit) ? "tag-pass" : "tag-fail";
var statusText = (netGbps <= interfaces[i].limit) ? "Compatible" : "Insufficient";
compatList.innerHTML += '' + interfaces[i].name + ': ' + statusText + '';
}
document.getElementById('results').style.display = "block";
}