HDMI TMDS Clock Calculator

Compute HDMI TMDS (Transition-Minimized Differential Signaling) clock and data rates for common resolutions and HDMI versions.

Calculator Electronics Updated Apr 23, 2026
X Facebook LinkedIn Reddit Email
How to Use
  1. Enter video resolution, frame rate, and color depth (8/10/12 bit).
  2. Tool computes TMDS clock, total data rate, and required HDMI version.
Input
Hz
Presets
TMDS Rates
Pixel Clock
—
TMDS Clock
—
Total Rate
—
Min HDMI
—

Show Work

Pick resolution.

Formulas

Pixel clock
f_pixel = H·V·f_frame·1.25
1.25 = blanking overhead.
TMDS clock (8-bit)
= f_pixel
1:1 ratio.
TMDS 10/12-bit
f_pixel × depth/8
Deeper color = faster clock.
Data rate/lane
TMDS × 10 (8b10b)
One bit per sub-pixel.
Total rate
Data rate × 3 lanes
RGB channels.
HDMI 2.1 FRL
Up to 48 Gbps
4 lanes × 12 Gbps.

History of HDMI

HDMI 1.0 (December 2002) defined TMDS signaling at 165 MHz - sufficient for 1080p60 8-bit color. Each subsequent version raised the maximum pixel clock: 1.3 (2006) to 340 MHz for deep color, 2.0 (2013) to 600 MHz for 4K60, 2.1 (2017) abandoned the TMDS clock lane and switched to 48 Gbps FRL (Fixed Rate Link) to support 8K60 and 4K120. The original TMDS encoding from Silicon Image uses an 8b/10b mapping designed to minimize transitions and maintain DC balance over inexpensive passive cables.

About This Calculator

Pick resolution, frame rate, and color depth. The tool computes pixel clock (active pixels + 25% blanking overhead), TMDS clock (scales with color depth), total data rate across the 3 RGB lanes, and minimum required HDMI version.

For HDMI 2.1 Fixed-Rate Link at 8K/120 Hz, the encoding changes to 16b/18b with embedded clock. For display simulation, many video test patterns can be generated by FPGAs (Xilinx, Lattice) with integrated HDMI transmitter PHYs. Everything runs client-side.

Frequently Asked Questions

What is TMDS?

Transition-Minimized Differential Signaling — HDMI\'s physical layer. Each color channel (R, G, B) is 8 bits, encoded to 10 bits for DC balance + transition minimization. One TMDS clock = one pixel.

HDMI versions?

HDMI 1.4: max 340 MHz TMDS (1080p60 10-bit HDR). HDMI 2.0: 600 MHz (4K60 8-bit). HDMI 2.1: 12 Gbps per lane (4K120, 8K60).

Lane count?

HDMI 1.x/2.0: 3 TMDS data lanes + 1 clock lane. HDMI 2.1 FRL (Fixed Rate Link): 3 or 4 data lanes, no separate clock (embedded).

Common Use Cases

1080p60 8-bit

148.5 MHz TMDS — HDMI 1.3+. Baseline HDTV.

4K60 10-bit HDR

594 MHz TMDS — needs HDMI 2.0 Premium High-Speed cable.

8K60 12-bit

HDMI 2.1 FRL at 48 Gbps; requires Ultra High-Speed cable.

Last updated: