It’s an HDMI cable. Since the initial letter of the abbreviation HDMI (High-Definition Multimedia Interface) sounds like "eich", we use "an".

It’s an HDMI cable. We put "an" before words that begin with a vowel sound. Since the initial letter of the abbreviation HDMI (High-Definition Multimedia Interface) sounds like "eich", we use "an".

I need to buy an HDMI cable.

I need to buy a HDMI cable.

Remember, when choosing between a and an, it's the sound (not the spelling) which is important.

Before buying an HDMI cable, you should check the size of the connector.

Follow the same convention with other related phrases that contain the acronym HDMI, such as an HDMI port, an HDMI connection, an HDMI connector, an HDMI input, etc.

What is an HDMI port used for?

An HDMI connection can either be single-link or dual-link.

Similarly, we say an H, an HDL level (High-Density Lipoprotein), an HIV infection, an HPV test, an HTML server, and an HTTP request.