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What Are the Different Uses for a 3.5mm Headphone Jack?

Alex Newth
Alex Newth

A 3.5mm headphone jack, sometimes called a 1/8-inch headphone jack by American users, is a versatile jack found in many modern electronics. While specified as a headphone jack, the 3.5mm headphone jack is able to perform a variety of different operations. This jack can be used to transfer video when used with camcorders and smartphones, and to hook up game systems to a TV. Amateur radios use this jack as a speaker-microphone, and some microphone units for musicians use this input. While not as popular as a universal serial bus (USB) port, this jack also is used to transfer data with some devices.

Mostly commonly, the 3.5mm headphone jack is used for headphones and earbuds. If someone is using headphones to listen to audio from a computer, a miniature music player, early compact disc (CD) or cassette tape player, or nearly any other device that plays audio, a 3.5mm jack is likely being used. The only exception is mobile phones, which commonly use 2.5mm jacks. A 3.5mm jack is able to create either mono or stereo sound, depending on the audio source.

Earbud headphones and a 3.5 mm headphone jack.
Earbud headphones and a 3.5 mm headphone jack.

When a camcorder or smartphone records video, it needs to output that video to make it watchable on a TV. Direct output methods commonly use a 3.5mm headphone jack, because the jack is able to output both sound and video. Depending on the cable, there will either be mono or stereo sound outputted. These same cables are used to connect digital video disc (DVD) players and many game systems for TV use and to connect stereos to large audio players.

Along with transferring sound, a 3.5mm headphone jack also can be used as an audio input. In this arena, mostly amateur radio operators use this jack; some mobile phones also use this to carry audio. Early microphones, and some modern versions, for musicians use the 3.5mm jack. These are used mostly to record onto cassette tape with mono sound, but some are able to record to CDs or to input the sound into a computer.

Data transfer is common for many devices, because they hold pictures, files and other documents that need to go from the device to a larger computer. The most commonly used jack here is a USB port, because it is more versatile for this, especially with computers. While USB is more popular, the 3.5mm headphone jack is used with some devices, the most common being graphing calculators and some amateur radios.

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Discussion Comments


I have always turned off electrical devices prior to unplugging 3.5mm jacks, being under the impression that as an electrical current is passing through it, it is the safest thing to do to avoid and damage to the devices.

Is this correct or is there none or minimal risk of damage to either device? For example, is it safe to unplug 3.55mm headphone jack from a computer without turning off the computer first?


@NathanG - Yeah, most people who buy flat panels want surround sound, not something that is limited to a headphone. But it’s up to you what you want.

I listen to a small radio every night when I go to sleep. It has a 3.5 stereo jack and I plug earphones into it. It works great.

Sometimes you have to be careful with these jacks, however, because you can jolt and twist them so that they no longer work properly. You can’t fix them in that case and need a new radio.


@SkyWhisperer - You’ll never believe this, but when my wife and I first were in the market for a flat panel TV, she insisted that the TV have a 3.5 audio jack on it.

She wanted the ability to listen quietly – or have other people in the room listen quietly. You’d think that with flat panel TVs you shouldn’t care, but she did, and there were in fact some TV models that had the jack.

One day we made a purchase thinking that the flat panel TV had such a jack, only to find out when we got home that it didn’t. I didn’t want to return the TV because it was otherwise a great set, but she insisted. It went back to the store; and I got the strangest look when I explained why I was returning it.


I have a 3.5 mm plug jack on my camcorder. Just as the article says, I can hook up this jack from the camcorder to the TV to get real time video playback. I use a special set of RCA cables to do this.

The cables are the same kind you have for video recording, one for audio and one for video. However they are adapted for camcorders. One end of the cables has a single wire that plugs into the jack, while the other end of the cables splits into the two audio and video wires to plug into the television.

I can play back my video, and I can also use it in reverse. That is, I can play what is playing on my television through my camcorder. This gives me the ability to record directly from the television directly to video tape. It’s cumbersome, but it works.


I guess I learned something today. I never had any idea why my graphing calculators always had a jack like that on them. It isn't like they make sound, so I could never figure it out. I've never taken the time to try to download programs onto them, so I never really thought about how the whole process works. That is pretty interesting, though. It seems like I have seen other things, too, that had a spot for a stereo jack, and I could never figure out what the purpose was.

I thought I would just mention, though, that you can tell what kind of capabilities your jack has just by looking at it. If you never notice the end, there are different rings that go around it. If there is just one ring, the headphones will only play in mono. Two rings means it will play in stereo, and three or four rings means there is some other use such as a microphone.

I only figured this out, because when I was younger, I bought a new pair of headphones, and they would only play in mono. I was complaining to my friend about it and, much to my embarrassment, he just pushed them in a little bit more, and they started working fine. Turns out I didn't have the jack plugging in all the way and only one of the rings was connected.


@TreeMan - To answer your question, yes, they do make jack adapters to go between the different sizes. I think the 3.5 jacks are going to be around for a while, though. They are small enough to fit into almost anything, and have the capability to do everything we need them to do. The main reason USB cables keep getting smaller is because the smaller cables can transfer data quicker.

I am not a tech expert, though. I am wondering if another type of adapter exists that converts a 3.5 mm jack into USB format. It seems like that would be something convenient to have if you needed to take video from an older camcorder and put it onto a computer. I would say that type of adapter has to exist, otherwise, there would be no way for people to do that.


Interesting. I decided I would go and check some of the cables from the stuff I have lying next to my computer. Both my iPod and cell phone both use the 3.5 mm audio cables instead of the smaller one mentioned in the article. Maybe with the newer electronics, the smaller cable is getting phased out because it isn't as functional. Now, a lot of people want their headsets to have a microphone on them (which is the case with all of my things). Maybe you can't use the smaller jack if you have a microphone.

It seems like that could really start to cause a problem, though, if there is a transition phase where everyone is switching over to different jacks. It is kind of like the problem with USB cables. They keep getting smaller and taking different sizes, so you're constantly having to find one that will fit. Do they make 3.5 to 2.5 adapters if you needed to plug one type of jack into another input?


Wow, I never knew that those jacks could do so much and that there were so many different kinds depending on what type of equipment you had. I knew there were smaller ones like for headphone and then the larger ones like for guitars and stereo equipment, but I didn't know there was the even smaller 2.5 mm kind.

I never really do any video recording, so I was not aware that the 3.5 jacks were able to carry any type of video through them. I thought that was only for USB cables. When I stopped to think about it, though, it made sense. Before computers, people still had video cameras, and they needed some way to be able to send the videos to different mediums. Whenever you send video through a smaller cable like that, is there any sort of compression or loss associated with it? Also, how long does it take? Even uploading videos from a camera to a computer with a USB cable can take a little while sometimes.

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    • Earbud headphones and a 3.5 mm headphone jack.
      Earbud headphones and a 3.5 mm headphone jack.