How we work out the answers
The standards table
Every page is generated from one table of facts about each standard: link rates, line coding, connector, power levels, cable ratings and lengths. We wrote it ourselves from the published specifications and the standards bodies' own summaries (USB-IF, Intel, the HDMI Forum and HDMI Licensing Administrator, VESA, Apple), and checked each value by hand. We don't copy text from specifications or other sites. Where we're not yet sure of a detail, the page says "being verified", the detail is listed below, and it's never used in a computed verdict.
The bandwidth formula
A display link has to send every pixel of every frame, plus the blanking interval, a timing gap at the end of each line and frame that the standards still require:
pixel clock = horizontal total × vertical total × refresh ratedata rate = pixel clock × bits per pixel
Bits per pixel are 3 × the bit depth for full colour (RGB or 4:4:4), 2 × for 4:2:2 and 1.5 × for 4:2:0. HDMI 1.4/2.0 always sends 4:2:2 in a 24-bit container.
Which timing
- VESA CVT reduced blanking v2 (CVT-R2) for monitors, DisplayPort, USB-C, Thunderbolt and HDMI 2.1 FRL. It uses 80 pixels of horizontal blanking and at least 460 µs of vertical blanking per frame.
- CTA-861 TV timing for HDMI 1.4 and 2.0, for the standard TV formats (1080p, 4K and 8K at their usual rates). These send much more blanking: 4K 60 Hz is 4400 × 2250 pixels per frame, a 594 MHz clock.
What a link carries
We compare the data rate with each link's usable rate after line coding: 8b/10b keeps 80% (HDMI TMDS, DisplayPort up to 1.4), 16b/18b keeps 88.9% (HDMI 2.1 FRL), and 128b/132b keeps about 97% (DisplayPort 2.1, minus a little for error correction). The full list is on the bandwidth page.
Display Stream Compression
DSC is modelled as compressing up to 3:1, never below 8 bits per pixel, which is the range monitors commonly use for "visually lossless" output. Real products choose their own ratio, and both ends must support DSC. A "With DSC" verdict means the mode fits if they do.
Limits of the model
- Monitors can use custom timings with less blanking than CVT-R2, so a real product can sometimes reach 1–2 Hz more than we compute (see the 98 Hz case below).
- HDMI 2.1 FRL packs blanking more efficiently than TMDS. We use reduced blanking for it, and that matches known working setups, such as 4K 120 Hz 10-bit on 40 Gbps ports.
- We don't model audio or auxiliary data, which takes a small share of the blanking time, or multi-stream overheads.
Validation
Before publishing, we computed these figures with the same code that builds the site and compared them with widely published values. The build stops if any of them drifts.
| Case | Computed | Published | Check | Reference |
|---|---|---|---|---|
| 1080p 60 Hz, 8-bit (CVT-R2) | 3.2 Gbps | 3.2 Gbps | Exact | VESA CVT-R2 data-rate tables (as reproduced in common DisplayPort references) |
| 1080p 60 Hz pixel clock (CTA-861 TV timing) | 148.5 MHz | 148.5 MHz | Exact | CTA-861 format 16, 2200 × 1125 total |
| 1440p 144 Hz, 8-bit (CVT-R2) | 14.08 Gbps | 14.08 Gbps | Exact | VESA CVT-R2 data-rate tables |
| 4K 60 Hz, 8-bit (CVT-R2) | 12.54 Gbps | 12.54 Gbps | Exact | VESA CVT-R2 data-rate tables |
| 4K 60 Hz pixel clock (CTA-861 TV timing) | 594.0 MHz | 594.0 MHz | Exact | CTA-861 4K60 format, 4400 × 2250 total; the reason HDMI 2.0 is 18 Gbps (594 × 3 × 10 bits = 17.82) |
| 4K 120 Hz, 8-bit (CVT-R2) | 25.82 Gbps | 25.82 Gbps | Exact | VESA CVT-R2 tables; known to just fit DisplayPort 1.4 (25.92) |
| 4K 144 Hz, 10-bit (CVT-R2) | 39.19 Gbps | 39.19 Gbps | Exact | VESA CVT-R2 data-rate tables |
| 5K 60 Hz, 8-bit (CVT-R2) | 22.18 Gbps | 22.18 Gbps | Exact | VESA CVT-R2 tables; why early 5K monitors needed two DisplayPort 1.2 streams (17.28 each) |
| 8K 60 Hz, 10-bit (CVT-R2) | 62.06 Gbps | 62.06 Gbps | Exact | VESA CVT-R2 data-rate tables |
| Highest 4K 10-bit refresh on DisplayPort 1.4 without DSC | 97 Hz | 98 Hz | ±1 | First 4K HDR gaming monitors (2018) ran 98 Hz in 10-bit 4:4:4; they used slightly tighter custom blanking than CVT-R2 |
| Highest 4K refresh on two DisplayPort 1.2 lanes (USB-C hubs) | 30 Hz | 30 Hz | Exact | Widely reported "4K 30 Hz" limit of DP 1.2 USB-C hubs (highest standard rate that fits; the raw maximum is 41 Hz) |
Being verified
These details are shown on their pages as provisional until we've checked them against the primary text:
- USB 3.2 Gen 1 (5 Gbps): Maximum passive A-to-B length: the USB 3 spec sets electrical limits rather than a length; about 3 m is the common practical figure.
- USB4 (20 and 40 Gbps): Which features are mandatory on USB4 v1 hosts (DisplayPort tunnelling vs DP Alt Mode, PCIe tunnelling): stated here as DP required, PCIe optional; re-check against the USB4 spec text.
- USB4 Version 2.0 (80 Gbps): That every existing USB4 40Gbps *passive* cable is guaranteed to run at 80 Gbps: USB-IF stated this at launch; confirm wording.
- Thunderbolt 3: Whether all early active TB3 cables lack USB 3.x: true for first-generation active cables; later ones added it.
- Thunderbolt 4: Whether Thunderbolt 4 cables are allowed to be EPR (240 W) rated: Intel's spec lists 100 W; some newer cables claim both.
- Thunderbolt 5: Minimum charging power a Thunderbolt 5 host port must accept (140 W is often quoted).
- Thunderbolt 5: Intel's headline display examples (three 4K 144 Hz; dual 6K): confirm wording before quoting specific counts.
- Thunderbolt 5: Passive Thunderbolt 5 cable length of 1 m.
- HDMI 2.2: Exact usable payload of 96 Gbps FRL (coding not yet checked; not used in calculations).
- HDMI 2.2: Headline maximum resolutions (e.g. 4K 480 Hz, 12K 120 Hz, 16K 60 Hz with DSC) as published by the HDMI Forum.
- HDMI 2.2: Whether Ultra96 is a separate label from Ultra High Speed at retail.
- DisplayPort 1.2: Typical passive cable length at full HBR2 rate (2 m guaranteed; about 3 m common in practice).
- DisplayPort 2.1 (and 2.0): Passive DP80 length (~1 m) and DP80LL length (~2 m).
- DisplayPort 2.1 (and 2.0): Exact usable figures 38.69 / 52.22 / 77.37 include FEC/framing overhead per published tables; raw 128b/132b alone gives 38.79 / 52.36 / 77.58.
- Lightning: Peak charging figure for the largest Lightning iPhones (about 27 W) as commonly measured; Apple states only "fast charge to 50% in 30 minutes".
- Lightning: Lightning blade dimensions (about 6.7 × 7.7 × 1.5 mm) are approximate; Apple does not publish a drawing.
- Can Thunderbolt 4 run two 4K monitors?: External display limits for specific Apple silicon chips change by generation; checked only as a general warning.
Updates
The site is rebuilt every week, and whenever a standard changes, a new one is published or a reader reports an error. Every verdict on the site is recomputed on each build.