Bandwidth Calculator

Not every HDMI or DisplayPort cable — or every port on your GPU, monitor, or TV — can carry every combination of resolution, refresh rate, and color depth. Each interface version has a hard bandwidth ceiling measured in gigabits per second (Gbps), and the signal you're asking it to carry has its own bandwidth requirement based on how many pixels you're pushing, how often you're refreshing them, and how much color data rides along with each one. This bandwidth calculator computes that requirement and checks it against every common HDMI and DisplayPort standard, so you know before you buy a cable or blame a "faulty" monitor whether your setup is even physically capable of the signal you're trying to run.

Understanding Video Bandwidth: The HDMI and DisplayPort Signal Formula

The bandwidth a display signal needs is a direct product of four numbers: how many pixels are in each frame, how many frames are sent per second, how many bits of color data ride on each pixel, and how much of that color data chroma subsampling strips out. Multiply them together and divide by a billion to convert from bits to gigabits, and you get the required link bandwidth in Gbps: Use the backlight bleed test in a darkened room to identify whether backlight bleed is within acceptable limits for your use case.

Bits per pixel comes from color depth: 8-bit color uses 24 bits per pixel (8 bits × 3 color channels), 10-bit uses 30 bits per pixel, and 12-bit uses 36 bits per pixel. Chroma factor comes from chroma subsampling: 4:4:4 (full color) uses a factor of 1, 4:2:2 uses 2/3, and 4:2:0 uses 0.5 — because subsampling shares color information across neighboring pixels instead of sending unique color data for every single one.

Worked Example: Does 4K120 4:4:4 10-bit Fit Over HDMI 2.1?

Take a 3840×2160 (4K) signal running at 120 Hz with 10-bit color (30 bits per pixel) at full 4:4:4 chroma:

1. Pixels per frame: \(3840 \times 2160 = 8{,}294{,}400\)
2. Bits per second: \(8{,}294{,}400 \times 120 \times 30 = 29{,}859{,}840{,}000\)
3. Convert to Gbps: $$29{,}859{,}840{,}000 \div 1{,}000{,}000{,}000 \approx 29.86 \text{ Gbps}$$

That 29.86 Gbps requirement fits comfortably under HDMI 2.1's 48 Gbps ceiling and DisplayPort 2.0's 77.37 Gbps ceiling — but it exceeds both HDMI 2.0 (18 Gbps) and DisplayPort 1.4 (25.92 Gbps). This is exactly why a 4K120 10-bit HDR signal works on an HDMI 2.1 port but gets rejected — or silently downgraded — on an older HDMI 2.0 port.

Worked Example: Why Consoles and GPUs Drop to 4:2:0 at 4K120

Run that same 4K120 10-bit signal but with 4:2:0 chroma subsampling instead of 4:4:4 (chroma factor 0.5 instead of 1):

$$8{,}294{,}400 \times 120 \times 30 \times 0.5 \div 1{,}000{,}000{,}000 \approx 14.93 \text{ Gbps}$$

That 14.93 Gbps requirement now fits under HDMI 2.0's 18 Gbps ceiling. This is precisely why game consoles and older GPUs connected over an HDMI 2.0 port automatically switch to 4:2:0 chroma when you enable 4K at 120 Hz with HDR — it's the only way to fit the signal through a link that can't carry full 4:4:4 color at that resolution and refresh rate.

Worked Example: 1080p 144Hz for Competitive Gaming

A common esports setup — 1920×1080 at 144 Hz, 8-bit color, 4:4:4 chroma — needs far less bandwidth: \(1920 \times 1080 \times 144 \times 24 \div 1{,}000{,}000{,}000 \approx 7.17 \text{ Gbps}\). That's well within the 10.2 Gbps ceiling of even HDMI 1.4, which is why older cables and ports have no trouble driving high-refresh 1080p displays.

How Chroma Subsampling and Color Depth Affect Required Bandwidth

Chroma subsampling reduces bandwidth by sharing color (chrominance) data across multiple neighboring pixels while still sending full brightness (luminance) data for every pixel — a trick the human eye tolerates well because it's far more sensitive to brightness detail than color detail.

4:4:4 vs 4:2:2 vs 4:2:0 Explained

• 4:4:4 (full color, chroma factor 1): every pixel gets its own full color and brightness data. Highest bandwidth requirement, sharpest text and fine color detail — the standard for desktop/productivity use and PC gaming where crisp text matters.
• 4:2:2 (chroma factor 2/3): color data is shared horizontally across pairs of pixels, cutting the color data by roughly a third. Common in professional broadcast and video production workflows.
• 4:2:0 (chroma factor 0.5): color data is shared across 2×2 blocks of pixels, cutting the color-related bandwidth in half. Standard for consumer video (Blu-ray, streaming, broadcast TV) and the automatic fallback when a resolution/refresh combination exceeds the link's 4:4:4 bandwidth.

Why 10-bit and 12-bit HDR Signals Need More Headroom

HDR content is typically delivered at 10-bit color depth (30 bits per pixel) rather than standard 8-bit (24 bits per pixel) — a 25% bandwidth increase before refresh rate or chroma are even considered. Some professional and next-generation displays support 12-bit (36 bits per pixel), a 50% increase over 8-bit. This is why enabling HDR on a display that was previously running fine at standard dynamic range can suddenly trigger a forced chroma downgrade or a refresh-rate drop — the extra color depth pushed the total bandwidth requirement past the link's ceiling.