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Fast, quick, or quickly
Fast is about speed, quick describes something short, and quickly is the adverb for doing something in a short time.
Quick rule
Speed? Fast, adjective or adverb. Something brief before a noun? Quick. How you do something, with a verb? Quickly. Quick to + verb: reacting soon.
High in speed. It is both an adjective and an adverb, and it never takes -ly: a fast car, drive fast.
Done or happening in a short time. It is an adjective: a quick call, quick to answer.
In a short time. It is an adverb, so it describes a verb: answer quickly, quickly realize.
How to choose
| Question | fast | quick | quickly |
|---|---|---|---|
| Is it about how fast something moves (a ___ train)? | Yes | SometimesSometimes | No |
| Is it about something that takes little time (a ___ question)? | SometimesSometimes | Yes | No |
| Can it come before a verb (She ___ closed the door)? | No | No | Yes |
| Can it go after the verb to say how (She runs ___)? | Yes | SometimesSometimes | Yes |
Why it trips people up
Fast works as both adjective and adverb, quick is an adjective for something brief, and quickly is the adverb with -ly. Writers mix them up because fast looks like it should take -ly and quick can be used as an informal adverb.
How each one works
Fast
Adjective: fast + noun
She is the fastest swimmer on our team.
Adverb, no -ly
Don't walk so fast. I can't keep up.
The speed of a connection
Our hotel has fast Wi-Fi, so video calls never freeze.
A clock that is ahead
Your watch is five minutes fast.
Quick
Quick + noun: it takes little time
I'll make a quick call before dinner.
Quick to + verb: reacts soon
He is quick to forgive.
A very short moment
Do you have a quick minute?
Quickly
Before the verb
Mia quickly packed the suitcase and ran to the bus stop.
After the verb
The ice cream melted quickly in the sun.
With verbs like realize
I quickly realized I had the wrong address.
What comes next
fast plus noun
They built a fast road across the valley.
verb plus fast
That river runs fast in spring.
quick plus noun
I only need a quick look at the menu.
quick to plus verb
Our daughter is quick to laugh.
quickly plus verb
The crowd quickly left the stadium.
verb plus quickly
Fill out the form quickly, please.
Set phrases
Fast
- fast forward
- to move a video or song ahead at high speed
- fast track
- a quicker way to reach something, skipping some steps
Quick
- quick learner
- a person who understands new things in a short time
- make a quick buck
- to earn money fast and without much effort
Quickly
- as quickly as possible
- in the shortest time you can
- quickly and easily
- in a short time and without trouble
Almost the same
We took a fast train to Seville.
The train moves at high speed.
We took a quick trip to Seville.
The trip is short.
We got to Seville quickly.
We arrived in a short time.
My uncle is a fast talker.
The speed of his speech.
My uncle is quick to answer.
He reacts soon.
My uncle answered quickly.
Adverb: it describes how he answered.
In a conversation
- A:
Is the new internet really fast?
- B:
Yes! I downloaded a whole movie quickly last night.
- A:
Great. Then I need a quick favor: can you send me that file?
- B:
Sure. I'll do it fast, before dinner.
Common mistakes
Wrong: The company is fastly growing.
Right: The company is growing fast.
Fast is already an adverb, so fastly is not used. A common slip when a writer expects every adverb to end in -ly.
Wrong: She is quickly to help anyone.
Right: She is quick to help anyone.
After be, the word describes the person, so it is the adjective quick, not the adverb quickly.
Memory trick
Follow what you are describing. The speed of something that moves is fast, which never takes -ly. Something short before a noun (a call, a look) is quick. How an action is done, next to a verb, is quickly.
It depends
- Quick as an adverb
- In casual speech, Come quick! is common. Oxford labels it informal, so in formal writing quickly is the safer choice.
- Other meanings of fast
- Oxford also lists fast for something that happens without delay (a fast response), firmly fixed (fast asleep), and ahead of time (a fast watch). The first one overlaps with quick.
FAQ
What is the difference between fast and quick?
Fast is about speed: a fast car, a fast connection. Quick is about something that takes little time: a quick call, a quick look.
What is the difference between quick and quickly?
Quick is an adjective that goes before a noun (a quick call). Quickly is an adverb that describes a verb (she answered quickly).
Is it faster or quicker?
Both exist: faster is the comparative of fast, and quicker is the comparative of quick.