When you have lots of bandwidth, you can deal with anything life throws at you. But, when you are really busy or seriously worried, you might not have the bandwidth to deal with any additional issues. You simply do not have the time or mental space.

We have other expressions that mean almost the same thing as being out of bandwidth. I can say I’ve hit my limit. I'm up to my neck, up to my eyes or up to my ears (you can use any of those body parts) with work, responsibility or fill in the blank. I am swamped!

“Bandwidth” can also simply mean your attention span.

For example, let’s say you are sitting at your dinner table thinking about an all-consuming problem. In this state, you are not able to focus on anything else. So, if someone tries to ask you a question, you can tell them, “Sorry. I do not have the bandwidth to talk to you right now. Come back in about an hour!”

Now, sometimes we use the word “bandwidth” when we talk about our brains as computers. An article in Scientific American gives us a good example of this usage.

Writer R. Douglas Fields discusses the development of an electronic device worn on the arm that permits the wearer to mentally interact with a computer. He writes, “This achievement opens and expands the bandwidth of the brain’s output.”

Sometimes people use “bandwidth” to simply mean mental ability. I might say: “Oh, do not to try to explain the issue to Alex. He doesn’t have the bandwidth for something so difficult.” Used this way, it means "Alex" is not intelligent enough to understand. It is a clear insult. So, be careful using it that way.

Now, let’s hear "bandwidth" used in this short conversation between two friends.

Okay, let’s go over the shopping list. We don’t want to forget anything.

Do we have to do that right now?

No. But the party is next month. So, time is running out.

There’s plenty of time. And right now … I have a lot on my mind.

Come on. You can’t be that busy.

Oh really? Well, today at work, I lost all my documents when my computer crashed.

Well, you have back-ups of all your documents, don’t you?

No. I had just finished writing three long stories. I’ll have to work overtime the rest of the week or I’ll miss my deadline!

Maybe we should change the subject.

Sure. This morning my sister called to tell me that my great aunt died.

Oh, I’m so sorry.

That’s okay. I only met her once when I was 10. But my mom can’t take care of the funeral plans. So, now I have to.

Oh. That’s going to take a lot of time.

Yes, it is. But that’s not all. Last night, my apartment flooded from a leak in the pipe! So, I have to fix it by tomorrow because my boss is coming over for an important dinner meeting!!

Wow. You are swamped! Really up to your neck.

Tell me about it! So, please understand if I don’t have the bandwidth right now to plan for a party that is a month away!!

Well. Sounds like someone is out of patience as well as bandwidth.

frequency – n. technical : the number of times that something (such as a sound wave or radio wave) is repeated in a period of time (such as a second)
band – n. a range of frequencies (as of radio waves)
data – n. information in digital form that can be transmitted or processed
attention span – n. the length of time during which one (such as an individual or a group) is able to concentrate or remain interested
all-consuming taking all of a person's time and attention : being the only thing a person thinks about
swamped – n. to cause (someone or something) to have to deal with a very large amount of things or people at the same time — usually used as (be) swamped