Quick Answer: HDMI stands for High Definition Multimedia Interface, and the port you are looking at is almost always Type A: 19 pins, a shell 13.9 mm wide, rated for 18 Gbit/s under version 2.0 and 48 Gbit/s under 2.1. The other sizes are Type C (mini, 10.4 mm), Type D (micro, 6.4 mm) and Type E (automotive, locking). Type B, with 29 pins, is obsolete. All current types carry the same 19 signals, so an adapter changes the shell, not the bandwidth.
Pin count is the number that governs the purchase. Nineteen pins cover four differential pairs, the display data channel, the consumer electronics control line and 5 V at 50 mA. Because the count is identical across sizes, the practical limit on an adapter chain is mechanical wear and signal quality, not the number of contacts. A chain of two adapters adds about 1.5 dB of loss and one more failure point.
The four letter sizes in use
Type A is the domestic standard found on televisions, laptops and consoles. Type C, often sold as mini, appears on cameras and tablets with a 10.4 mm shell that is rated for fewer mating cycles than Type A. Type D, the micro size, is 6.4 mm wide and used on action cameras. Type E adds a locking shell and a sealed housing for vehicle and industrial panels.
| Port type | Contacts | Shell width | Where it appears |
|---|
| Type A | 19 | 13.9 mm | television, laptop, console |
| Type C (mini) | 19 | 10.4 mm | camera, tablet, drone |
| Type D (micro) | 19 | 6.4 mm | action camera, phone |
| Type E | 19 | 12 mm, locking | vehicle, sealed panel |
| Type B | 29 | 21 mm | dual link, obsolete |
What the 19 pins actually carry
Video and clock
Three data pairs plus one clock pair occupy pins 1 to 12. Under version 2.0 each pair runs 6 Gbit/s for 18 Gbit/s total; version 2.1 replaces the scheme with four lanes at 12 Gbit/s for 48 Gbit/s. A cable rated for high speed is therefore mandatory above 10.2 Gbit/s, and the difference is measurable at 5 metres.
Control, power and Ethernet
Pins 13 to 19 carry consumer control, the display data channel at pins 15 and 16, 5 V at pin 18 and hot plug detect at pin 19. The +5 V rail is limited to 50 mA, which is enough for an EDID chip and nothing else. A device that tries to draw 500 mA from that pin will brown out the source.
Adapters, chains and bandwidth
Passive versus active
A mini to full size adapter is passive: it changes the shell only, and the bandwidth stays that of the cable behind it. An adapter that converts between formats, such as a scaler or a splitter, is active and needs its own supply. Two passive adapters in series are acceptable once; three is a repair waiting to happen.
Format conversions
Where one source must feed two displays, a splitter duplicates the stream and copies the EDID of the least capable screen, so a 4K panel paired with a 1080p panel runs at 1080p. For that decision, compare the options in this guide to the best hdmi splitter before ordering, and check whether the unit supports HDCP 2.2 downstream.
Choosing a port, a cable and a version
Match the cable to the format, not to the connector. A 4K60 signal at 18 Gbit/s needs a premium high speed hdmi cable at 3 metres or less, while 1080p60 works on standard speed to 10 metres. The version differences that matter in a rack are set out in hdmi 1.4 vs 2.0, and the short answer is that 1.4 caps at 10.2 Gbit/s and no HDR metadata path.
Practical scenarios
- Situation: a camera with a Type C socket feeding a 15 metre run to a switcher – use one passive Type C to Type A adapter at the camera and a fibre cable after that, not a chain of three adapters.
- Situation: a 4K60 player at 12 metres (40 ft) from the display – drop to 4K30 or fit a fibre cable; copper at 18 Gbit/s is unreliable beyond about 5 metres.
- Situation: a rack panel where the plug is pulled twice a day – specify Type A with a locking screw, because a Type C shell is rated for far fewer mating cycles.
- Situation: a vehicle panel with vibration and washdown – Type E with its locking shell and seal, never a Type A plug retained by friction alone.
FAQ
Does the full form include the version number?
No. High Definition Multimedia Interface is the interface name, and 1.4, 2.0 and 2.1 are revisions of the specification behind it. The port moulding is identical across revisions, so a version claim on a connector tells you nothing without a cable test.
Can a Type C plug go into a Type A socket?
Not directly. The shells differ by 3.5 mm and the contacts sit on a different pitch, so a passive adapter is required. Use one adapter at the device end and keep the rest of the run as a single cable.
What happens if a port is damaged?
A bent pin 18 or 19 usually shows as no picture and no hot plug detection, while a shorted data pair gives sparkles or a pink screen. Replace the port or use a short tail cable, because bending the shell back rarely restores contact.
