All HDMI cables are not made equal. In this section, I'll cover the differences in HDMI cables including:

• Connector shapes / types
• Cable versions and associated data speeds and resolutions 
• How to identify a cable type based on packaging labels

Connector Types

There are five HDMI connector types.

• Type A is known as "Standard" and is the most common. It has 19 pins.
• Type B is called "Dual-Link" and is not used in many modern products. In the past it was used with high-resolution devices due to it having 29 pins however as of August 2021, it has not yet been used with any products.
• Type C is known as HDMI Mini and is used to connect to portable devices like digital cameras and camcorders. It has 19 pins like that of the HDMI Standard connector.
• Type D is "micro" and is often used with Raspberry Pi 4, and GoPros, amongst other devices like portable monitors. It has 19 pins as well.
• Lastly, Type E is used for connecting a video output device to an automotive entertainment system or display. It's almost identical to type A however it has a locking tab to keep the cable from vibrating loose as well as to help prevent moisture and dirt from interfering with the signals.

HDMI versions and associated speeds

There have been numerous upgrades to the HDMI standard since its inception in 2002 with HDMI 1.0. Check out the full list of all the HDMI versions of the past below:

• 1.0 (2002)
• 1.1 (2004)
• 1.2 (2005)
• 1.2a (2005)
• 1.3 (2006)
• 1.3a (2006)
• 1.4 (2009)
• 1.4a (2010)
• 1.4b (2011)
• 2.0 (2013)
• 2.0a (2015)
• 2.0b (2016)
• 2.1 (2017)

HDMI Versions and Categories

Any time you buy a new cable, the packaging will indicate which type of HDMI cable it is with one of the below labels. If you already own a cable, the cable itself should have the type specified but not always. Below are the different HDMI cable types determined by the logo seen on the packaging of the cable from the HDMI Forum. What mainly separates each version and category are the differences in bandwidth (in Gigabytes Per second), display resolution (in pixels), and refresh rate (in Hertz). These topics are covered in more detail further down this page.

• "Standard" or Category 1 - Designed to handle most home applications and tested to transmit 1080i/720p video. Most of these cables have been replaced by the High-Speed HDMI Cables but there are still some in the marketplace and consumers should note while fine for some uses, they don’t support the later resolutions, refresh rates, and bandwidth requirements.
  • Associated HDMI versions: 1.0, 1.1, 1.2
  • Max bandwidth: ~5 GBPS
  • Max resolution: 1080p (1920 x 1080) @ 60 Hz

• High-Speed or Category 2 - Designed and tested to support video resolutions of 1080p and more, including display technologies such as 4K UHD, 3D, and Deep Colour. This is a recommended cable if you are using any of these technologies or connecting your 1080p display to a 1080p content source e.g. a Blu-ray Disc player. These cables will be distinguished with a "High Speed" label on the packaging
  • Associated HDMI versions: 1.3, 1.4
  • Max bandwidth: ~10 GBPS
  • Max resolution: 4K (3840 x 2160) @ 30 Hz

• Premium High-Speed HDMI or Category 3 - Special certification designations for High-Speed HDMI Cables that have been designed/certified for reliable performance for 4K and UltraHD. This includes advanced features such as HDR, 4K60, expanded color spaces including 4:4:4 chroma sampling and BT.2020. They have low EMI and identify them by the HDMI Licensing Administrator’s Premium HDMI Cable Certification Label for authentication verification.
  • Associated HDMI versions: 2.0
  • Max bandwidth: 18 GBPS
  • Max resolution: 4K (3840 x 2160) @ 60 Hz

• Ultra High-Speed (also Category 3) - This is the cable with the highest resolution and bandwidth (at the time of this writing). It can reach up to an 8K resolution with 48 GBPS. The Ultra-High Speed cable is often used in console and PC gaming as it provides the best quality at the highest bandwidth possible.
  • Associated HDMI versions: 2.1
  • Max bandwidth: 48 GBPS
  • Max resolution: 8K (7680 x 4320) @ 60 Hz

Certifications to look for when purchasing cables

Only products featuring this official anti-counterfeit label have been certified as part of the Premium HDMI Cable Program. Each certified product label will feature a unique QR code & holographic fingerprint which can be scanned and verified using the HDMI smartphone app.

Are HDMI cables backward compatible?

Yes. Ultra High-Speed HDMI cables are backward compatible with older HDMI devices, and older cables are compatible with new HDMI 2.1 devices, though the full 48 Gbit/s bandwidth is only supported with the new cables.

What is Resolution? What is 4K?

The display resolution or display modes of a digital television, computer monitor or display device is the number of distinct pixels in each dimension that can be displayed.

HDMI resolutions:

• High Definition
  • 720p (1280 × 720 pixels) HDMI 1.0 and up
  • 1080p (1920 × 1080) HDMI 1.0 and up
• Ultra High Definition (UHD)
  • 4K UHD (3840 × 2160) HDMI 1.3 and up
  • 8K UHD (7680 × 4320) HDMI 2.1

What is Refresh Rate?

A refresh rate is the number of times a new image is shown on a screen (such as a television or computer monitor) per second. It is measured in hertz (Hz), which is a measurement of frequency. This means that a screen with a refresh rate of 60 Hz will show 60 images per second.

Bandwidth or Bit Rate

This is the number of bits (0s and 1s) that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second.

For example, here are the max HDMI Bit Rates and Refresh rates at 4K resolution (for the versions that can support it). Notice how the bandwidth and refresh rate increase as the versions and categories move up when the resolution stays the same.

• Category 2: HDMI 1.3 & 1.4 - High Speed @ 4K
  • data rate: 10 GBPS
  • refresh rate: 30 Hz
• Category 3: HDMI 2.0 - Premium High Speed @ 4K
  • data rate: 18 GBPS
  • refresh rate: 60 Hz
• Category 3: HDMI 2.1 - Ultra-High-Speed @ 4K
  • data rate: 48 GBPS
  • refresh rate: 120 Hz

Color Space and Depth

One bonus specification that is often included in HDMI version information is color capabilities. This includes color "space" and "depth".

Color space is the range of colors represented in an image. The two main color spaces used to represent digital video are RGB and YCbCr. 

Color Depth is the number of bits used to represent the color of a single pixel and determines the amount of shading or gradation in the pixel. Color depth is expressed as BPC or Bits Per Channel.

Color Differences in HDMI Categories

Category 1

max color depth support: 8 BPC

color space support: YCbCr 

Category 2

max color depth support: 16 BPC "true color"

color space support: xvYCC 

Category 3 

max color depth support: 16 BPC "true color"

color space support: sYCC(601) 

The original HDMI design provided support for 24-bit Color Depth (8 bits per color x 3 RGB colors). HDMI 1.3 introduced "True Color" which added support for 10, 12, and 16 BPC. The human eye can differentiate about 10 million different colors, and 24-bit color has roughly 17 million colors. Thus 24-bit color or 8BPC is more than sufficient.

Moving Ahead

Now that you know all the different HDMI categories and their specs, let's take a look at some different HDMI applications and when you'd need an Ultra-High-Speed cable as opposed to a High-Speed cable.