HDMI bandwidth calculator
No picture, a blank screen that flickers, or 4K 120 Hz greyed out in the settings: many HDMI problems are bandwidth problems. This calculator works out how much data a video format needs and which HDMI version, port speed and certified cable can carry it.
Results are estimates for planning. Check the manufacturer's manual before you drill, buy or mount anything.
How it works
HDMI 1.4 and 2.0 (TMDS) send every pixel of the frame including the blanking interval, on three data channels with 8b/10b encoding:
TMDS rate = pixel clock × (bits per channel ÷ 8) × 3 channels × 10 bits
The pixel clock comes from the standard CTA-861 timing for each format (for example 594 MHz for 4K 60 Hz). 4:2:2 travels in the same space as 8-bit RGB at any bit depth up to 12; 4:2:0 halves the rate. HDMI 1.4 tops out at a 340 MHz TMDS rate (10.2 Gbps) and HDMI 2.0 at 600 MHz (18 Gbps).
HDMI 2.1 (FRL) uses 16b/18b encoding on three or four lanes at 3 to 12 Gbps each, up to 48 Gbps. We estimate the FRL rate from the active picture: width × height × refresh × bits per pixel × 18/16.
Assumptions and limits
- The FRL figure is an estimate: audio, packet overhead and blanking add a little, so a format just under a tier's limit may still need the next one.
- HDMI version numbers on a box do not guarantee every feature. Check the port's maximum rate in the TV, receiver or console manual.
Sources
- HDMI 2.1 specification overview (HDMI Licensing Administrator)
- Ultra High Speed HDMI Cable (HDMI Licensing Administrator)
- CTA-861, A DTV Profile for Uncompressed High Speed Digital Interfaces (video timings)
Last reviewed: November 2026.