"Fast" describes continuous high speed; "quick" describes brevity or a short burst of speed.
Moving or happening at a high continuous speed.
She is a very fast runner — she won every race this season.
Ella es una corredora muy rapida. Gano todas las carreras esta temporada.
The train travels fast, reaching 300 km/h on this route.
El tren viaja rapido, alcanzando 300 km/h en esta ruta.
Time passes fast when you are having fun.
El tiempo pasa rapido cuando te estas divirtiendo.
Taking little time or done without delay. Brief, prompt.
Can I ask you a quick question? It will not take long.
¿Puedo hacerte una pregunta rapida? No tardara mucho.
Let us have a quick meeting before the presentation.
Tengamos una reunion breve antes de la presentacion.
She is a quick learner — she picked it up in two days.
Ella aprende rapido. Lo captó en dos dias.
Common mistake
Using "quickly" as an adjective: "He is a quickly driver" is wrong. Correct: "He is a fast driver." Also: "quick" rarely works as an adverb in formal English — "Drive quick" is informal. The correct adverb is "quickly" or simply "fast" (which does not change form).
Trick to remember it
Trick: "quick" almost always precedes a noun and describes something brief ("a quick look, a quick call, a quick meal"). "Fast" describes the speed itself ("a fast car, run fast, fast internet"). If you can substitute "quick" with "brief", use "quick". If you can substitute "fast" with "rapid", use "fast".
Quick rule
Fast = continuous high speed. Quick = short duration / without delay.
Did you know?
"Fast" has a little-known opposite meaning: in Old and modern English, "fast" also means "firmly fixed / not moving" (as in "hold fast" = hold firmly, or "fast asleep" = deeply asleep). And "fast" as a noun or verb means fasting ("to fast" = to abstain from food, "a fast" = a period of fasting). One word with three almost opposite meanings.
Exercise 1 · Pick the right one
He is the _____ typist in the office. He never has to look at the keyboard.
Exercise 2 · Pick the right one
Can we have a _____ chat after class? I have a question about the assignment.
Exercise 3 · Form the word
Fast = continuous high speed. Quick = short duration / without delay.
Using "quickly" as an adjective: "He is a quickly driver" is wrong. Correct: "He is a fast driver." Also: "quick" rarely works as an adverb in formal English — "Drive quick" is informal. The correct adverb is "quickly" or simply "fast" (which does not change form).
Trick: "quick" almost always precedes a noun and describes something brief ("a quick look, a quick call, a quick meal"). "Fast" describes the speed itself ("a fast car, run fast, fast internet"). If you can substitute "quick" with "brief", use "quick". If you can substitute "fast" with "rapid", use "fast".
Bryan López
Founder of SpeakUP Academy