How to Use “Fast” vs “Quickly” in English | Speak More Clearly

追加: 2026-05-09

[00:00:00]Welcome back, everyone. My name is Maya, and you are listening to Speak English Fluently, the place where we practice simple, natural English for real life.

[00:00:09]If you enjoy learning English in an easy way, make sure you subscribe and stay with us. And I'm Ben, and today I already feel like this lesson is going to save me from making mistakes. Good, because listen to this situation. You are late for work. Your friend calls and says, "Where are you?" You want to answer, "I'm coming fast." Or maybe, "I'm coming quickly." But suddenly you stop and think, "Wait, which one sounds right?" That happens to me. Sometimes I say, "Please drive quickly." And sometimes I say, "Please drive fast." I don't know if both are correct. Exactly.

[00:00:47]Today we're going to talk about two small words that learners mix up a lot, fast and quickly. They both mean something happens with speed, right?

[00:00:57]Yes, but they are not always used in the same way. The good news is, this is not difficult. You only need a few simple rules. I like simple rules. Complicated grammar makes my brain run away. Then rule number one is this. Fast can describe speed directly. We often use fast after verbs like run, drive, walk, speak, move, or grow. So, I can say, "She runs fast." Perfect. She runs fast sounds natural. And he drives fast.

[00:01:32]Correct, but be careful. Driving fast can be dangerous. True, especially if my uncle is driving. Everyone in the car starts praying. Very real example.

[00:01:44]Now, rule number two, quickly usually means in a short time or without delay.

[00:01:50]It focuses more on how soon something happens. So, if I say, "Please answer quickly." It means don't wait too long?

[00:01:59]Exactly. Please answer quickly means answer soon, don't delay. What about please answer fast? People may say it in casual speech and many will understand it, but quickly sounds more natural and clear in that sentence. So fast is more about speed and quickly is more about time. That's a great simple way to remember it. Fast is speed, quickly is short time or no delay. Let me try. The car moved fast. Good. I finished my homework fast. That is common in conversation, but I finished my homework quickly sounds better and more natural.

[00:02:39]Why? Because finishing homework is an action that happens in an amount of time. You mean you finished it in a short time, so quickly fits better. I finished my homework quickly. Much better. But if I say the train goes quickly, is that wrong? Not wrong, but the train goes fast sounds more natural because you're talking about the train's speed. Ah, okay. Machine, person, or vehicle moving with speed, fast. Yes.

[00:03:10]For example, this bus is fast. My brother runs fast. That dog moves fast.

[00:03:17]The internet is fast. The internet is fast. I love that sentence. But sometimes my internet is not fast. It's emotionally slow. Emotionally slow is not grammar, but I understand the pain.

[00:03:32]So what about this sentence? Can you speak fast? That means can you speak at high speed, but for English learners, I usually say, "Please don't speak too fast." Very useful. Yes. Now compare that with can you speak quickly? That can sound like can you finish speaking soon?" It's a little different. Oh, that's interesting. Speak fast means speed of words. Speak quickly can mean, "Don't take too long." Exactly. Let's do a guided practice loop. I'm ready. I'll give you an idea, you make a sentence.

[00:04:09]First idea, a runner in a race. The runner ran quickly. Not terrible, but better. The runner ran fast. We're describing the runner's speed. The runner ran fast. Great. Next idea, you sent a message and your friend replied after 1 minute. My friend replied fast.

[00:04:31]Again, people say that, but the clearer sentence is, "My friend replied quickly." My friend replied quickly.

[00:04:39]Nice. Next idea, a child is growing and becoming taller. The child is growing quickly. Good. Here, quickly works because we mean it is happening in a short time. Can I also say, "The child is growing fast?" Yes, that is also very natural. Some sentences allow both.

[00:05:00]Wait, both? Now my brain came back and got confused again. Don't worry, some common expressions use either one.

[00:05:08]Growing fast and growing quickly both sound natural, but fast feels a little more casual and direct. Quickly feels a little more careful or formal. So, fast is often more everyday? Yes, fast is very common in daily speech. Quickly is also common, but it sounds a bit cleaner when we talk about doing something in a short time. Give me daily phrases. Sure.

[00:05:34]Here is our first phrase pack today.

[00:05:37]Number one, drive fast. Drive fast.

[00:05:41]Number two, don't drive too fast. Don't drive too fast. Number three, speak slowly, not too fast. Speak slowly, not too fast. Number four, please answer quickly. Please answer quickly. Number five, I'll be back quickly. I'll be back quickly. Number six, that was a quick answer. That was a quick answer. Good.

[00:06:07]Notice there, quick is an adjective.

[00:06:10]We'll talk more about quick later. Okay, quick is different from quickly. Right.

[00:06:16]Number seven, he learns fast. He learns fast. Number eight, she finished quickly. She finished quickly. Number nine, this phone charges fast. This phone charges fast. Number 10, let's leave quickly. Let's leave quickly.

[00:06:36]Excellent. Now, mini quiz time. I'm nervous, but in a friendly way. Choose fast or quickly. Number one, my sister talks very blank. My sister talks very fast. Correct. Number two, please come here blank. Please come here quickly.

[00:06:55]Good. Come here quickly means come now, don't wait. Number three, this sports car is really blank. This sports car is really fast. Perfect. Number four, I cleaned the kitchen blank because guests were coming. I cleaned the kitchen quickly because guests were coming.

[00:07:15]Excellent. Number five, don't eat too blank. You'll feel sick. Yes, eating fast means eating with too much speed.

[00:07:25]This is already clearer. Fast is speed, quickly is no delay or short time.

[00:07:32]That's the main idea for part one, but we are not finished yet. In the next part, we'll talk about common mistakes, natural American examples, and when fast and quickly can both work. And maybe we can save learners from saying, "I did it fastly." Oh, yes. Important warning, don't say fastly. That word is not used in normal English. Good. Fastly is going in the trash. Exactly. Welcome back.

[00:08:01]Let's continue from where we stopped. In part one, we learned the big idea. Fast is usually about speed, and quickly is usually about doing something in a short time. And we also threw fastly in the trash. Yes, very important. Please do not say fastly. Native speakers do not normally use it. So, I should not say, "He runs fastly." Correct. Say, "He runs fast." And not, "She drives fastly."

[00:08:34]Right. Say, "She drives fast." This is actually funny because many English words become adverbs with l y. Slow becomes slowly, quick becomes quickly, careful becomes carefully, but fast stays fast. Exactly. That is why learners make this mistake. The pattern looks normal, but fast is special. It can be an adjective and an adverb. Wait, adjective and adverb? Simple explanation. An adjective describes a noun. For example, a fast car. The word fast describes the car. A fast car. An adverb describes an action. For example, the car moves fast. Here, fast describes how the car moves. So, fast can do both jobs. Yes. A fast runner. That is an adjective. The runner runs fast. That is an adverb. Nice. Fast is doing double duty. Exactly. But quickly is only an adverb. It describes an action. So I can say she answered quickly. Yes. But I cannot say she gave me a quickly answer.

[00:09:52]Correct. That is wrong. You should say she gave me a quick answer. Ah, so quick is the adjective, quickly is the adverb.

[00:10:01]Perfect. Let's compare three words now.

[00:10:05]Fast, quick, and quickly. Okay, this is the grammar family. Yes. Fast means high speed. Quick means done in a short time.

[00:10:16]Quickly means doing something in a short time. Give me examples. Sure.

[00:10:22]That is a fast car. The car has high speed. That is a fast car. That was a quick meeting. The meeting was short.

[00:10:30]That was a quick meeting. We finished the meeting quickly. We finished it in a short time. We finished the meeting quickly. Excellent. Now let's talk about a common real-life situation, ordering food. My favorite grammar topic. Imagine you're in a coffee shop. You are late.

[00:10:49]You tell your friend, "I need a quick coffee." That means I need coffee in a short time. Yes. You are not saying the coffee runs at high speed. A fast coffee would be scary. Exactly. So we say a quick coffee, not usually a fast coffee.

[00:11:07]What about make my coffee quickly? That means please make it without delay. It is grammatically correct, but be careful with tone. It can sound a little rude if you say it too directly. So maybe could you make it quickly, please? I'm in a hurry. Much better. Adding please and a reason makes it softer. I'm in a hurry.

[00:11:29]That's a useful phrase. Yes. I'm in a hurry means I don't have much time. So, in daily life, can we have a quick coffee and could you make it quickly, please? Perfect. Now, another situation, work emails. Oh, no. Emails are dangerous. Imagine your boss says, "Can you quickly check this file?" That means check it now or spend a short time checking it. Right. It does not mean move your eyes at racing speed. So, quickly check is natural. Yes. We often use quickly before verbs like check, call, send, reply, finish, explain, and look. Let me try. I'll quickly send the email. Great. Can you quickly call me?

[00:12:16]Very natural. Let me quickly explain.

[00:12:20]Excellent. That is a very common phrase.

[00:12:23]I hear people say that in videos, "Let me quickly explain." Yes. It means I will explain this in a short time. Could I say, "Let me fast explain?" No, that sounds wrong. Good. Never say fast explain. Right. Use quickly explain.

[00:12:40]Okay, rule. With actions like explain, reply, check, send, finish, use quickly.

[00:12:48]Very good rule. Now, let's talk about physical movement. If someone moves their body at high speed, fast is usually natural. Like, he runs fast.

[00:12:59]Yes. She walks fast. The dog moves fast.

[00:13:02]The train goes fast. Can we say, "She walks quickly?" Yes, we can. But, there's a small feeling difference. She walks fast focuses on speed. She walks quickly can feel like she's walking because she needs to arrive soon. So, if she's naturally a fast walker, say she walks fast. Yes. And if Maya walked quickly to the office, sounds like Maya was in a hurry. Perfect. You got it.

[00:13:31]Nice. My English brain is loading faster now. Faster, yes, good use. We use faster as the comparative form of fast.

[00:13:41]Comparative means comparing two things.

[00:13:44]Exactly. This car is faster than that car. My phone charges faster now. Please speak slower, not faster. Can I say more quickly? Yes. More quickly is the comparative form of quickly. For example, she finished more quickly than I expected. But in daily speech, do people say faster more? Often, yes. In casual conversation, people may say finish faster or move faster or reply faster. But in clear, careful English, reply more quickly can sound better. So, casual, reply faster. More careful, reply more quickly. Yes, but don't overthink it. For A2 and B1 learners, focus first on natural daily patterns.

[00:14:33]Good, because overthinking is my special talent. Let's do another practice loop.

[00:14:39]Ready. I'll say a situation, you make the sentence. Situation one, your friend is talking too fast and you can't understand. Please don't speak too fast.

[00:14:49]Excellent. Very natural and polite. Or could you speak more slowly, please?

[00:14:55]Even better. That is softer and more polite. Situation two? You need to leave the house in 5 minutes. We need to leave quickly. Perfect. Could I say we need to leave fast? People may say it, but leave quickly sounds clearer. Okay. Situation three? Your laptop starts in 5 seconds.

[00:15:16]My laptop starts quickly. Good. You could also say my laptop is fast if you mean the laptop works at high speed in general. So, starts quickly is about one action. Is fast is about general speed.

[00:15:30]Exactly. That's a strong difference.

[00:15:33]Situation four. Your cousin eats his dinner in 3 minutes. My cousin eats fast. Good. You can also say he ate quickly because he was late. Ah, if it's his habit, he eats fast. If it was because he had no time, he ate quickly.

[00:15:52]Excellent. That is a very natural way to think about it. I like this. It feels less like grammar and more like meaning.

[00:15:59]That's the goal. English becomes easier when you connect grammar to real situations. Let's do a phrase pack for part two. Great idea. Repeat these daily use phrases. Number one, let me quickly check. Let me quickly check. Number two, I'll quickly send it. I'll quickly send it. Number three, can you reply quickly?

[00:16:22]Can you reply quickly? Number four, she learns fast. She learns fast. Number five, you're talking too fast. You're talking too fast. Number six, that was a quick call. That was a quick call.

[00:16:36]Number seven, we made a quick stop. We made a quick stop. Number eight, he fixed it quickly. He fixed it quickly.

[00:16:45]Number nine, this charger is fast. This charger is fast. Number 10, the line moved quickly. The line moved quickly.

[00:16:54]Great. Notice the line moved quickly is natural because we mean the waiting line did not take too long. But the car moved fast is about speed. Exactly. Mini quiz?

[00:17:08]Yes. Choose the best word. Fast, quick, or quickly. Number one, I need a blank shower before work. I need a quick shower before work. Correct. Number two, please text me blank when you arrive.

[00:17:23]Please text me quickly when you arrive.

[00:17:26]Good. Number three, my new bike is really blank. My new bike is really fast. Correct. Number four, she gave me a quick smile and left. She gave me a quick smile and left. Perfect. Number five, the kids ran blank across the yard. The kids ran fast across the yard.

[00:17:48]Very natural. Ran quickly is also possible, but ran fast sounds more everyday. So, sometimes more than one answer can work, but one answer sounds more natural. Exactly. That's why we practice with real situations, not just grammar rules. My recap. Fast is speed.

[00:18:08]Quick describes a short thing. Quickly describes an action done in a short time. And fastly is still in the trash.

[00:18:18]Perfect recap. In part three, we'll practice more natural conversations, common mistakes, and a final speaking challenge for the listener. Welcome back. Let's finish today with natural conversations, common mistakes, and a final speaking challenge. I'm ready. My confidence is moving fast. Nice sentence. Moving fast sounds natural.

[00:18:42]Good. I was scared you were going to say, "Ben, put that in the grammar trash." Not this time, but we do have some mistakes to fix. First mistake, he drives quickly when you mean his normal driving speed. Better, he drives fast.

[00:18:59]Yes, he drives fast means his speed is high. But, listen to this.

[00:19:05]He drove quickly to the hospital. That can mean he didn't waste time because the situation was urgent. So, drives fast is general speed. Drove quickly can be connected to urgency. Exactly. Second mistake. I need to do a fast call. Hmm, that sounds a little strange. Right.

[00:19:27]Say, I need to make a quick call. I need to make a quick call. Perfect. We use quick before nouns when the thing is short or doesn't take much time. A quick call, a quick shower, a quick meeting, a quick question. Excellent. Now, third mistake. Please quick send me the file.

[00:19:49]Wrong word order? Yes. Say, please send me the file quickly or can you quickly send me the file? Can you quickly send me the file? Great. In daily English, quickly can come before the verb or after the object. Both are common. So, I'll quickly check it and I'll check it quickly are both okay? Yes. I'll quickly check it sounds very natural in conversation. Let me quickly check. I'll quickly call him. I'll quickly reply.

[00:20:22]These feel useful. Very useful. Now, let's build a real conversation. Imagine you and I are leaving the house late in the morning. Okay. I'm putting on one shoe and holding coffee. Very realistic.

[00:20:37]I say, Ben, we need to leave quickly.

[00:20:40]The bus comes in 5 minutes. And I say, okay, I'll quickly grab my keys. Good.

[00:20:46]Then I say, don't walk too fast. I can't carry this bag and run. So, we need to leave quickly but not walk too fast.

[00:20:55]Exactly. See the difference? Leave quickly means don't delay. Walk too fast means your walking speed is too high.

[00:21:04]That is actually clear. Same situation, different meaning. Now, another real conversation. You're at work, your manager asks for a small update. I say, "Sure, let me quickly explain." Good.

[00:21:18]The project is moving fast, but we still need one more day. Excellent. Moving fast means progress is happening at high speed. And let me quickly explain means I'll explain in a short time. Perfect.

[00:21:33]Now, let's do a natural speaking practice. I'll say a sentence with a mistake and you fix it. Let's do it.

[00:21:40]Number one.

[00:21:41]My brother runs quickly in races.

[00:21:44]Better, my brother runs fast in races.

[00:21:47]Correct. Number two. I have a fast question. I have a quick question. Good.

[00:21:54]Number three. Can you fast check this email? Can you quickly check this email?

[00:22:00]Excellent. Number four. This app opens fastly. No, fastly. This app opens fast or this app opens quickly. Great. Both can work there. Opens quickly sounds a little cleaner. Opens fast sounds casual and natural. Number five. Number five.

[00:22:20]She gave a quickly answer. She gave a quick answer. Perfect. Now, let's give listeners a simple memory trick. I need this.

[00:22:31]>> [snorts] >> Think like this. Fast is about speed you can feel or see. A fast car, a fast runner, a fast speaker, fast internet.

[00:22:41]Speed you can feel or see. Nice. Quickly is about time. Do it quickly, reply quickly, finish quickly, leave quickly, check it quickly. And quick is before a noun. A quick call, a quick lunch, a quick meeting, a quick question.

[00:22:59]Exactly. That one simple system will help you a lot. Let's make a final phrase pack. Great. Repeat these. Don't speak too fast. Don't speak too fast.

[00:23:12]Could you say that more slowly? Could you say that more slowly? I'll quickly send you the address. I'll quickly send you the address. Let's make a quick stop. Let's make a quick stop. This train is fast. This train is fast. She finished the test quickly. She finished the test quickly. He learns fast. He learns fast. Can I ask a quick question?

[00:23:37]Can I ask a quick question? Please reply quickly. Please reply quickly. The meeting ended quickly. The meeting ended quickly. Very good. Now, let's do the final mini quiz. Listeners, answer before Ben if you can. I feel pressure now. Number one. My phone charges very blank. My phone charges very fast.

[00:24:01]Correct. Quickly is also possible, but fast sounds very natural here. Number two. I need a blank answer. I need a quick answer. Correct. Number three.

[00:24:13]Please finish this blank. We have no time. Please finish this quickly. Good.

[00:24:20]Number four. The little boy ran blank to the playground. The little boy ran fast to the playground. Natural.

[00:24:28]Number five. Let me blank explain the problem. Let me quickly explain the problem. Perfect. Now, I have one question. What if I say do it fast? Is that wrong? Not wrong. It's common in casual speech, but it can sound direct or a little impatient. Do it quickly, please sounds more polite and clearer.

[00:24:51]So, tone matters, too. Yes. English is It's only grammar, it's also feeling. Do it fast can sound like pressure. Could you do it quickly, please? Sounds softer. That's important for daily life, especially at work. Exactly. Let's practice polite versions. Okay. Direct, send it fast. Polite, could you send it quickly, please? Good. Direct, talk fast. Polite, could you explain it quickly? Or if I need slower speech, could you speak more slowly? Excellent.

[00:25:27]Direct, I need a fast meeting. Natural, I need a quick meeting. Perfect. Now, final recap. Use fast when you talk about speed, like he runs fast, this car is fast, you speak too fast. Use quickly when an action happens in a short time or without delay. Reply quickly. Leave quickly. I finished quickly. Use quick before a noun when the thing is short, like a quick call, a quick question, a quick lunch. And never say fastly.

[00:26:01]Exactly. Now, audience question. What is one thing you do fast in daily life? Do you eat fast, walk fast, type fast, or learn fast? Try making one sentence in the comments. And also try one sentence with quickly. For example, I quickly check my messages in the morning. Great practice. If this lesson helped you speak more clearly, subscribe to Speak English Fluently, like the video, and share it with a friend who is learning English, too. And remember, don't learn fastly. Ben. Sorry. Don't learn fastly, learn clearly. Much better. Keep practicing, keep listening, and we'll see you in the next lesson.