Recommended level: Intermediate
Imagine you are at the airport. You have just returned from a trip, and you have called your friend to pick you up and drive you home. You step outdoors with your luggage and stand in the waiting area. Dozens of cars drive past you. You know your friend drives a white SUV, so you keep your eyes open, pay careful attention, and look for that specific car.
Another way to say this is that you keep an eye out for your friend's car.
This is just one example of this common English idiom. As the title of this page says, we are going to learn about the difference between two "keep an eye" idioms: keep an eye on something or someone, and keep an eye out for something or someone.
So, what's the difference between these phrases? Let's start with some definitions:
Keep an eye on something or someone - to keep something or someone under careful observation; to watch something or someone
Keep an eye out [for something or someone] - to look for something or someone with careful and patient attention; to be alert as you wait for or hope for something or someone
Okay, now let's look at these idioms one at a time with a variety of examples.
Keep an eye on something or someone
You can keep an eye on something you are cooking on the stove. You can keep an eye on a child. A guard in a prison can keep an eye on a prison inmate. In all of these cases, someone carefully observes something or someone else. When we keep an eye on something or someone, it's because we feel that thing or person needs our attention. If we don't keep an eye on it or them, something we do not wish to happen might happen. Let's take a look at some examples:
"Could you keep an eye on my backpack? I need to use the washroom." (In this case, maybe you are in a public place with a friend. Your friend needs to use the washroom, but they do not want to bring their backpack with them, so they ask you to watch it--probably to make sure no one steals it.)
"Keep an eye on the pasta for a few minutes. I need to go to my office and answer an urgent email." (In this case, someone is cooking pasta on a stove, and they want to make sure the water doesn't overflow or that the pasta doesn't become overcooked while they are responding to an email in their home office, so they are asking someone--probably their partner or roommate--to pay attention to the pasta.)
"Could you keep an eye on the kids on Saturday? It's my mom's birthday and I want to visit her." (In this scenario, someone is asking their partner, or perhaps their ex-wife or ex-husband, to watch their children on Saturday.)
"I'm keeping an eye on this online auction. I really want to win this video game." (In this scenario, someone is paying close attention to an online auction because they do not want someone else to win it and get the video game that the person is trying to get.)
"I'm keeping an eye on you, so you had better behave." (In this scenario, a parent is warning their child to behave because the parent is watching them closely and paying attention to their actions.)
"She's a capable employee, but sometimes she's a little lazy. You have to keep a close eye on her." ("Keep a close eye on someone" is a common variation which intensifies the phrase "keep an eye on someone." In this scenario, someone is talking about an employee who needs regular observation because sometimes the employee is a little lazy.)
As you can see, you can keep an eye on something or someone in a variety of scenarios. Essentially, if something or someone requires careful observation and external attention, it or they need someone to keep an eye on it or them.
Grammar note: This idiom always has an object. For example, you cannot say "I'll keep an eye" or "I'll keep an eye on." You must say "I'll keep an eye on it" or "I'll keep an eye on him/her/them/etc."
Finally, here are some variations of this idiom, as well as some similar words and phrases:
"Could you watch my backpack for a few minutes?"
"I'll keep a close eye on him."
"I've got my eye on you." (This means "I'm watching you." You can also say "I have my eye on you" or "I have my eyes on you.")
"She keeps a close watch on all of her employees."
"My dad looked after us after school." (This is a phrasal verb. If someone looks after you, they take care of you. This means they make sure you are safe and that your needs are met.)
Now, it's your turn to practice. Answer the following questions:
Who usually kept an eye on you when you were a child?
What is something you keep an eye on every day?
Do you regularly keep an eye on your email inbox to make sure it doesn't get too full?
Keep an eye out [for something or someone]
You can keep an eye out for new job postings online. You can keep an eye out for a friend who's coming to pick you up at your house. You can keep an eye out for cheap airplane tickets. In all of these cases, you are paying careful attention because you are looking for, waiting for, or expecting something or someone. You are alert and paying careful attention because you don't want to miss the thing or person that you are looking for.
Sometimes, the thing you are looking for is not guaranteed. For example, if you are online and you are keeping an eye out for a job posting that matches your qualifications, there is no guarantee that a company will post a job that you want. However, you are still keeping an eye out just in case it does happen. Let's take a look at some more examples:
"I'll keep an eye out for cheap concert tickets. Sometimes, the prices go down as the date of the concert gets closer." (In this scenario, the person is probably checking concert ticket prices online on a regular basis because the current prices are too high, and they are hoping to pay less.)
"Okay, I've ordered an Uber. Keep an eye out for a red Toyota." (This person has ordered an Uber driver to pick up him and his friends. He is telling his friends to look for a red Toyota.)
"I'm keeping an eye out for new job opportunities. Let me know if you see anything." (This person is open to changing their job, and they are asking their friends to help them.)
"My dad said his plane just landed. He should be here soon. Keep an eye out for a short guy in a red jacket." (In this scenario, your dad's plane has just arrived, and your dad has sent you a message to inform you of his arrival. He's wearing a red jacket, and you're telling the person who came with you to the airport what your dad looks like.)
"I'm going to keep an eye out for electronics deals on Boxing Day. I need a new laptop." (Boxing Day is on December 26th. Most retailers lower their prices significantly on this day to sell excess inventory that they didn't sell before the winter holidays. Many people keep an eye out for deals or lower prices on this day.)
"I'll keep an eye out for any signs of trouble." (In this scenario, perhaps the person speaking is a security guard at a public event who is saying that he will pay attention to the people at the event. He will be alert so that he can act quickly if there are any problems at the event.)
As you can see, if you keep an eye out for something or someone, you look for it or them. However, just remember that the thing or person you are keeping an eye out for is not guaranteed to appear.
Grammar note: "Keep an eye out" can be used by itself. For example, if your friend tells you that they are waiting for someone in a blue jacket, but your friend needs to go to the bathroom for a couple of minutes, you might say "Don't worry. I'll keep an eye out." If it's clear from the context who or what you are keeping an eye out for, it's possible to just use "keep an eye out" by itself.
Now, it's your turn to practice. Complete the sentences with your own ideas:
"I'm keeping an eye out for..."
"Could you keep an eye out for...?"
"I'll keep an eye out for..."
In short, if you keep an eye on something, you observe it carefully to make sure nothing bad happens to it, and if you keep an eye out for something, you stay alert so you don't miss what you are waiting for and/or looking for.
Finally, if you're keeping an eye out for practical English learning resources, and you want to support my work, consider picking up a PDF, e-Book, or paperback of one of my books. Thanks for learning English with me, and I wish you success in your studies!