HDMI & DisplayPort Bandwidth Calculator

Understanding the HDMI and DisplayPort bandwidth calculator — concept and principle

Every video mode needs a certain data rate between the graphics card or console and the display. This calculator estimates the uncompressed bandwidth for a given resolution, refresh rate and colour depth, then checks it against the usable capacity of common HDMI and DisplayPort versions.

About 32 Gbps is needed; only links above the red line carry it without DSC compression.

How it is calculated

Data rate (Gbps) = (width + 80) × (height + V) × refresh rate × bits per pixel ÷ 10⁹.

Width and height: active pixels. The 80 extra pixels per line and V extra lines follow VESA CVT reduced blanking (RB2): the vertical blank lasts at least 460 µs, so with v = 460 µs × refresh rate, V = ⌈height × v ÷ (1 − v)⌉, at least 15 lines.
Refresh rate: frames per second (Hz).
Bits per pixel: 24 for 8-bit RGB, 30 for 10-bit RGB, 36 for 12-bit RGB.

The result is compared with each link's usable payload after line coding: HDMI 1.4 8.16 Gbps, HDMI 2.0 14.4, HDMI 2.1 FRL 48G 42.67, DP 1.2 17.28, DP 1.4 25.92, and DP 2.1 UHBR10, UHBR13.5 and UHBR20 at 38.69, 52.22 and 77.37 Gbps.

The principle

A display is refreshed line by line, and between lines and frames there are short blanking periods that carry no picture but still occupy link time. Total pixels per second is therefore the full timing (active plus blanking) multiplied by the refresh rate, and each pixel carries its colour bits. Links lose part of their raw speed to coding: HDMI 2.0 and DP 1.4 use 8b/10b coding (80% efficient), so 18 Gbps becomes 14.4 and 32.4 becomes 25.92; HDMI 2.1 FRL uses 16b/18b, giving 42.67 of 48; DP 2.1 uses 128b/132b with additional overhead, leaving about 77.37 of 80.

Worked example

Inputs: 3840 × 2160, 120 Hz, 10-bit RGB (30 bpp).
Total width: 3840 + 80 = 3920 pixels.
Blanking share v = 0.00046 × 120 = 0.0552; extra lines 2160 × 0.0552 ÷ 0.9448 = 126.2, rounded up to 127, so 2287 lines.
Pixels per frame: 3920 × 2287 = 8,965,040.
Data rate: 8,965,040 × 120 × 30 = 32,274,144,000 bit/s ≈ 32.27 Gbps.
Comparison: too much for HDMI 1.4, HDMI 2.0, DP 1.2 and DP 1.4 without DSC; fits HDMI 2.1 (42.67) and all DP 2.1 UHBR rates.

How to read the result

"Fits" means the mode can run uncompressed with full RGB or 4:4:4 colour. "Needs DSC" means the link can still carry it only with Display Stream Compression, a visually lossless codec that can reduce the data by up to about 3:1, or with chroma subsampling (4:2:2 or 4:2:0) or lower colour depth.

Common mistakes

Assuming a port labelled HDMI 2.1 supports full 48G FRL; many TVs and monitors offer 40G or less.
Ignoring that HDR at 10-bit raises bandwidth by 25% over 8-bit.

Keep in mind: This is an approximation. Real timings depend on the display's EDID; some displays use longer blanking than the RB2 minimum, so the real requirement can be a few percent higher. Check your device's specifications.

Frequently asked questions

Does 4K 120 Hz 10-bit fit in HDMI 2.0?

No. It needs about 32 Gbps against 14.4 Gbps usable, so it requires HDMI 2.1, DSC or chroma subsampling.

Does cable length matter?

Yes. Long passive cables may fail at high data rates; certified Ultra High Speed HDMI or DP80-rated cables are safer.

Sources: HDMI Forum, HDMI Specification 2.1b · VESA, DisplayPort Standard Version 2.1 · VESA, Coordinated Video Timings (CVT) Standard

Exact timings depend on the display — treat this as a starting point and check the maker’s own chart.

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